So a new Doctor has taken the keys to the Tardis, after David Tennant's turn as the Time Lord came to an end.
The Master-packed finale to the hit show was on BBC1 on New Year's Day, and saw Matt Smith become the 11th Doctor after a regeneration.
So did David Tennant's final episode live up to your expectations? Did you shed a tear when the moment came?
And what about David Tennant as the Doctor? Have you enjoyed his version of the character, and are you looking forward to the new Time Lord too?
Unfortunately this topic is now closed but there are Comments pages on other subjects on the main Chat index.
"David Tennant was wonderful as the Doctor and played the role really well. They have made the wrong choice making him leave. I think they should have continued having David Tennant."
Natalie, 10, Oxfordshire, England
"David Tennant was a legend and played the 10th Doctor well. Matt Smith has great expectations to live up to but I like the catch phrase Geronimo that the 11th Doctor uses. I don't know why people stereotype him for his looks though."
Graham, 11, London, England
"I loved Doctor Who and I can't believe David Tennant is not going to be the Doctor any more I will miss him terribly because he was so funny."
Bethany, 10, Hampshire, England
"David Tennant was an absolute legend and it just won't be the same without him. I'm not sure about the new guy."
Angela, 14, London, England
"We like David Tennant more then Matt Smith, although we haven't seen much of the 11th Doctor yet. We think David should stay."
Jamie and Eden, 9 and 8, Newport, UK
"I think David Tennant was the best Doctor and Matt Smith has to live up to expectations! We're all going to miss David!!"
Emma, 12, Hull, England
"I won't bother turning my screen on once Matt Smith starts to release full-length episodes. I haven't seen much of David Tennant this past year, after all, he has only acted in four episodes! Shocking compared to how many he did last year. So no, I'm not much of a fan now it's 2010.
Zoe, 11, Bedfordshire, England
"He was an outstanding Doctor which puts immense pressure on Matt Smith. Good luck to him because it is going to be tough for him to be as good as Tennant."
Nathan, 11, Blackpool, England
"I cried during the episode. Lines from the 10th Doctor keep springing into my head! I think the new Doctor's cool, to be honest but I can't tell if he's as good. I adored David Tennant! I think it was more the writer's fault than the actors if he came across as being like David."
Claire, 12, England
"I didn't really like The End of Time. It was really silly that everyone turned into the Master. In the classic series that would never have happened. The Master was more sinister then, not hyper-active. As I've said in my previous comments, Tennant isn't that brilliant, not compared to other Doctors. Matt Smith will be fantastic, take it from someone who knows the classic series of Doctor Who and has been a fan their whole life. Weeping Angles, Silurians (from the classic series), Daleks (again?! At least they're grey like the classic series colour scheme) and Steven Moffat as head writer! Brilliant! A classic style series at last! "
Sam, 12, Norfolk, England
"We really liked Doctor Who and we were sad to see David Tennant go."
Rebecca and Rhys, 12 and 9, Manchester, England
"I don't normally watch Doctor Who but I did see the episode. It was fabulous I thought the Doctor was great!"
Molly, 11, Lancashire, England
"I think David Tennant was the best and I'm sad he has gone as I only started watching Doctor Who because of him. I also think Matt Smith is trying too hard to be as funny as David."
Scarlett, 12, Suffolk, England
"It was amazing! I cried at the end because I knew David wasn't coming back. I will always remember that episode. But I was amazed that the TARDIS went on fire when he changed! Although the Doctor's new catch phrase is Geronimo instead of the old one. But I'm still going to love it!!"
Megan, 11, Tunbridge Wells, England
"David Tennant was really good but to keep Doctor Who exciting they needed to get rid of him."
Lizzie, 12, Surrey, England
"I think David Tennant was really good at playing the part of Doctor Who. I'm sad that he had to go but I'm sure Matt Smith will be great as well."
Mikki, 8, Gloucestershire, England
"I think it was the best. I like the new Doctor better. The Weeping Angels are coming back as well as the Daleks, so I won't blink!"
Dominic, 9, Newcastle, England
"I don't really watch Doctor Who, but I do know that David Tennant was very good at his job. I'll still be upset to see him go, no matter whether I watch it or not."
Jessica, 10, London, England
"That was amazing, it was the best episode they have ever made, except for the fact that David Tennant was leaving! I have grown up with David as the Doctor, he is the one I will remember the most! I am a massive Doctor Who fan as I have a room full of Doctor Who stuff. Bring on the next series!"
Hannah, 13, Northamptonshire, England
"It was great to see Sarah Jane again and all the characters from the series in it. It was the best episode I have ever seen."
John, 10, London, England
"It was the best episode yet."
Tim, 8, London, England
"I thought it was BRILLIANT! David Tennant's performance was fantastic and I was really sad to see him go but I have seen Matt Smith in other things and I think he will be great"
Charlie, 12, Oxfordshire, England
"FANTASTIC episode, it was emotional too now that the 10th Doctor has regenerated. I'm not too keen on Matt Smith, but I think he'll be good, I'll just have to see him in action! It was very sad when the Time Lord said I don't want to go."
Ruhi, 14, Liverpool, England
"I was very sad when he regenerated after saying goodbye to all his friends. I cried a lot when he changed. I found Matt Smith incredibly annoying, I think David Tennant will always be the best Doctor. I thought the two final episodes were simply the best. They were funny, clever, scary, sad and made me feel for the characters. What else could I possibly want?! It was perfect!"
Emeline, 14, Northamptonshire, England
"Doctor Who will never be the same without David Tennant. He has been the best Doctor by far. The 11th Doctor looks absolutely rubbish! He's not the right guy for the job. "
Amy, 11, Norwich, England
"I loved David Tennant as the Doctor and I was sad to see him go, but I suppose he had to go sometime and Matt Smith looks like a good guy to take over from him. Anyway, David's not going to disappear, is he? I mean, everybody wants him on their show because he is so good!"
Mia, 11, Dunbartonshire, Scotland
"I think the 10th Doctor was the best, but lets see how the 11th Doctor turns out. I was very sad when I heard that David Tennant was going to leave the show."
Angela, 10, Glasgow, Scotland
"I miss David Tennant. I think it would have been better if David stayed as Matt Smith is not the best actor for the job!"
Ceri, 12, Swansea, Wales
"It is so sad that he changed. I think the new Doctor has a BIG reputation to uphold!"
Marija, 9, London, England
"David was the best. Matt has got a lot to live up to. He's trying so hard to be David but he's just not."
Faatimah, 9, Yorkshire, England
"I thought Matt Smith was fantastic. David Tennant is pretty good but it was definitely time for a change."
James, 11, Cheshire, England
"Well, I loved the last episode. I don't really care who the Doctor is, as long as the actor is a good one!"
Martha, 12, Brecon, Wales
"I personally loved the last episode. The script got a little bit lame in places, as did the acting, but it was hair-wrenching to see the Doctor so broken! I cried for ages!"
Avril, 13, Southend, England
"He is a very good Doctor and I want him to stay and come back as he is, because he is funny and serious at the same time."
Ryan, 8, London, England
"Well, I'm sad that David Tennant is leaving and I think he will always be the best Doctor. I think Sam from Norfolk is wrong!!"
Nai, 11, Wolverhampton, England
"I do agree that he should not have gone, because David was the best out of them all. He really should have stayed."
Lauren, 13, Manchester, England
"Matt Smith is OK but he will never be as good as David Tennant."
Eleanor, 11, Berkshire, England
"I was so devastated when David left and regenerated. I almost cried. I have watched the show since he began acting as the Doctor, so Matt had better be up to his standard."
Charlotte, 11, Manchester, England
"I think that Doctor Who is brill, I watch it all the time. I cannot believe that David Tennant is going."
Emily, 12, Yorkshire, England
"I'm really sad that David has left but I am also looking forward to the new series."
Tia, 11, Cornwall, England
"I found it quite emotional because it was David Tennant's last one ever. I feel so sad now that Matt Smith is taking over. He has to do a lot of hard work if he wants to have a big future."
Sophie, 11, Yorkshire, England
"It was AMAZING, although I don't think Matt Smith will be as good as David Tennant."
Keelin, 9, London, England
"Brilliant. It is sad that David isn't the Doctor anymore, but Matt Smith looks quite good."
Ian, 11, Glasgow, Scotland
The last episode was the BEST EVER! I felt so sorry for Wilf. The Time Lords were AWESOME. I was so sad to see David go and I don't think Matt was that good at the end, but the trailer looks OUTSTANDING."
Emily, 12, West Sussex, England
"I was extremely upset when David Tennant left, but when I saw what Matt Smith was like I wasn't bothered. I am so exited about the new Doctor Who series."
Ava, 11, Nottingham, England
"The last episode was so sad! I really like David Tennant as the Doctor, but I think Matt Smith could be just as good."
Eleanor, 12, Yorkshire, England
"I preferred it when the Doctor travelled around galaxies, exploring new planets and stuff, rather than saving the Earth from imminent destruction every week. It just seems to be running out of steam to me."
James, 13, East Sussex, England
"I think that people are judging Matt Smith harshly just because he is replacing David's role as the Doctor. To be honest, I think that he will play the character brilliantly in his own way and I will continue to watch Doctor Who, regardless of who may be the Doctor."
Danisha, 13, London, England
"The storyline was blended together really well. It is a shame that David Tennant is quitting but I'm still going to watch Doctor Who. Matt Smith does not look as good but he looks like he will fit into the role."
Callum, 11, Swindon, England
"I thought it was brilliant, I think Matt Smith will be as good as David Tennant."
Ryan, 14, Herts, England
"I have to say I have not been a big fan of Doctor Who but that Christmas special was brill!"
Lauren, 9, Rotchester, England
"It was absolutely AWESOME! I'm Doctor Who and David Tennant's BIGGEST Fan!"
Cassey, 11, London, England
"I don't see what everybody's making a fuss about, the Doctor regenerates - that's how the show goes. Any proper Doctor Who fan would just carry on regardless of who the Doctor is. It's silly that people are saying they are not watching Doctor Who any more because your favourite Doctor has left. My favourite Doctor, Sylvester McCoy, left in 1996 and I didn't complain!"
Sam, 12, Kings Lynn, England
"I think David Tennant was definitely the best Doctor ever. He was so weird and wacky! I am not sure about the new Doctor though. On the other hand we haven't really seen him acting yet so people might change their minds and think that he is really good too!"
Gail, 12, London, England
"I thought it was brilliant! It will be hard for Matt Smith to keep up David's personality as the Doctor though!"
George, 10, Surrey, England
"I don't see what everybody's making a fuss about. The Doctor regenerates, it is just how the show goes. Any proper Doctor Who fan would just carry on regardless of who the Doctor is. It is silly that people are saying they are not watching Doctor Who anymore because their favourite Doctor has left. It doesn't matter if the Doctor is ugly or rubbish. How can you even call Matt Smith rubbish if you've only seen him for 20 seconds? I personally will watch Doctor Who forever, regardless of who the Doctor is."
Sam, 12, Norfolk, England
"I thought it had a great storyline, and how the Doctor saved the world from the Time Lords was clever!"
Matthew, 12, Suffolk, England
"I think David Tennant was the best Doctor we have ever had, but I just cannot wait for Matt Smith! Me and my friend Louise are CRAZY about Doctor Who and we knew Matt Smith was coming and we couldn't wait. We really don't want to say goodbye to David Tennant."
Alice, 14, Hampshire, England
"It was amazing, the best ever episode of the whole time he has been on Doctor Who. The regeneration was so cool!"
Ryan, 12, Essex, England
"It was so cool but I cried all the way through because David will be leaving."
Lewis, 10, Cwmbran, Wales
"I think David Tennant is the best Doctor ever! My favourite bit of the whole last episode was when the Doctor regenerated into Matt Smith. I'm very sad David has left but I can't wait to see what Matt Smith has to offer."
Lauren, 14, Glamorgan, Wales
"I wanted to cry when David left. I think he has been the best Doctor of all time. Miss you David!"
Chloe, 11, Glasgow, Scotland
"I think David Tennant was the best Doctor they've had! I hope Matt is as good! I loved the last episode but thought it was so sad!"
Emily, 13, Nottingham, England
"It is really sad that David Tennant has left, he was the best Doctor EVER and I was lucky enough to grow up with him as the Doctor! Don't judge a book by its cover though, let Matt Smith do a couple of episodes before you judge him."
Laura, 13, Yorkshire, England
"I do not like Doctor Who, but I love Matt Smith, so I am going to watch it anyway!!"
Olivia, 14, Cumbria, England
"I loved David Tennant's last episode and I was crying the whole way through it. I'm not going to watch Doctor Who anymore because Matt Smith looks rubbish."
Rebecca, 11, Glasgow, Scotland
"The Doctor Who episode was fantastic. It was so great!"
Thomas, 7, Lincoln, England
"I think David Tennant has been the best Doctor ever and no Doctor will ever be as good as him. I don't think I can judge Matt Smith yet as I haven't seen much of him on Doctor Who."
Hannah, 12, Cardiff, Wales
"I was sad to see David Tennant leave and I was really sad because I thought he was one of the funniest ever. I will miss his episodes."
Danielle, 10, London, England
"I think that Matt Smith is too ugly and trendy to be the 11th Doctor. Please keep David Tennant on the show, he is the best."
Ethan, 10, West Midlands, England
"I think that David Tennant has been the best Doctor yet!"
Amy, 8, Devon, England
"I think it was amazing and I don't want David Tennant to go, he's the best Doctor ever!"
Jonathan, 9, Warwickshire, England
"I was so sad, I cried. I love him so much. I don't like the other Doctor but I need to give him a chance."
Katie, 12, Kent, England
"I don't think Matt Smith will be as good as David Tennant."
Callum, 11, Bolton, England
"I loved the last episode of Doctor Who, I thought David Tennant was brilliant and I think the new Doctor (Matt Smith) was absolutely awful. No match for David at all! I cried the whole way through!"
Lucy, 13, Oxfordshire, England
"Goodbye David Tennant! I thought David was definitely the BEST Doctor ever! I cried for ages when he regenerated. David added sooo much fun and excitement to the show. It is going to be very different without him. I'll miss you David!"
Finnia, 12, Bermuda
"It was really sad to hear that David Tennant was going and I think Matt Smith is a rubbish actor! I want David to come back!"
Bling, 10, England
"The final episode was GREAT best episode ever Matt Smith was FANTASTIC can't wait for the new series."
Millie, 13, Sussex, England
"I thought it was great and I'm starting to like the new Doctor, and I can't wait until the new Doctor but I will miss David."
Dijana, 10, Essex, England
"Doctor Who was amazing, but I don't like the new Doctor as much."
Eddie, 12, Harrogate, England
"It was OK, but not his best adventure."
Anna, 13, London, England
"Oh my god it was soooo sad, I don't like Matt Smith it made me cry."
Dushy, 15, Stoke-on-Trent, England
"I think it will be hard for the new doctor to follow after David Tennant as he was such a good Doctor."
Jessica, 12 , Northamptonshire, England
"Doctor Who was amazing! It was action-packed and it has probably been the best Doctor Who I've seen. But it was so upsetting to see the Doctor get so hurt and regenerating. I think he has been the best Doctor Dr Who has seen. David Tennant all the way!"
Amirah, 14, Cardiff, Wales
"It was awesome! such a great ending! I am going to miss David Tennant. He was a great doctor but I think Matt smith will be just as good!"
Estella, 11, Thatcham, England
"It was really great but it could have been better if David Tennant stayed!!!"
Praful, 12, Leicester, England
"What a finale the Master and The Time Lords all coming back and the end of time itself. Can't wait till Matt Smith's series is on. "
Ben, 9, Glasgow, Scotland
"This final episode was just a blast it really shows how well David Tennant had done and looks like Matt Smith will be a fantastic Doctor."
Laurence, 14, Camberley, England
"I thought the last episode was definitely worth waiting for. My heart was thumping like mad as I watched it and I enjoyed it so much. When it ended I couldn't believe that David Tennant was no longer the Doctor. Matt Smith has a lot to live up to but David will always be my favourite Doctor."
Rachel, 11, Sunderland, England
"Wow! I was shocked when the Doctor transformed into a different person. I was sad to hear that it was the end of the Doctor Who series as I was a fan of the series."
Samra, 12, Batley, England
"David Tennant is a good actor - I'm sad he had to go."
Hanan, 10, Northolt, England
"I think that David Tennant was one of the best Doctors ever! (and he still is) I am looking forward to Matt Smith because I want to find out if he as good as the 10th Doctor!!! "
Nilima, 13, Birmingham, England
"The final episode was definitely worth waiting for. I was flooding my living room with tears when he went to see past characters and when donna's grandfather got stuck in the glass room and told him to leave him there. David Tennant is and always will be my all time favourite doctor, he just added a young and cheeky element to the show I think it needed. I'm not entirely sure if I'm looking forward to Matt Smith because I haven't seen him act the doctor in a full length episode, but the thought of David Tennant leaving makes me shed a tear."
Abigail, 11, Cardiff, Wales
"Definitely worth the wait. I loved the part where he regenerates even though it looks like he's very angry. Matt Smith is not as bad as I thought he would be . Matt Smith is actually pretty good but I won't go saying much more about him because we've only just seen him as the Doctor. "
Natasha, 9, Bromley, England
"I thought that Doctor Who was amazing. i thought David Tennant was going to die. I did not want David Tennant to stop being Doctor who. "
Charie, 7, Romford, England
"I don't get emotional that often but the finale made me shed tears! I was so upset that this was David's LAST EVER episode! It was brilliant but I have doubts that the eleventh Doctor will be as good as David Tennant was!"
Annie, 11, London, England
"No no no no no no no David how could you have left?! This episode left me completely and utterly devastated. The tenth doctor will always be my doctor- I have so many memories of him! I hope they make a film with the clone doctor and Rose- that would make it seem not so bad."
Izzy, 16, London, England
"YES!!!!!! Wow it was great!!! I love David Tennant and looked away when he regenerated! But I think Matt Smith is good too, but no one can EVER replace David!"
Frankie, 12, Exeter, England
"Yes. It was definately worth watching and I don't think I'll like the next doctor."
Leanne, 10, Coventry, England
"I thought the episode was really good but I felt it got ruined when Matt Smith was introduced. "
"IT WAS AMAZING!!!!! I was nearly crying at the end but i didn't. David Tennant was great at being the Doctor and I hope Matt Smith is just as good!"
Owen, 11, Prestatyn Wales
"The first part was better than the second. The second part was very complicated and hard to follow, but it was very good."
Albie, 11, Radlett, England