Daniel Radcliffe plays Harry Potter in Harry Potter and the Goblet of Fire.
Newsround chatted with him to find out about the challenges of making the fourth film.
You can also watch our interview with Daniel in full by clicking on the Newsround Player link on the right and selecting Potter.
What were the biggest challenges for you on this one?
Physically the biggest challenge was doing all the underwater stuff, because when you get home at the end of the day you were exhausted. It is very, very tiring doing that, but it was fun, I'm glad I did it because I can look back and say I was underwater for about a month!
I suppose in terms of the acting challenges, all the stuff towards the end with Voldemort and then bringing Cedric back, those scenes were pretty tough to do but I really enjoyed doing them.
How did you get yourself emotionally into that last part of the film?
I can't really even remember. It's a process so you start off a certain place and a certain level and you draw on your own experiences.
Obviously none of my experiences have even come close to anything Harry has to deal with, but I sort of draw on the most upsetting thing that I can remember and then you refine it and refine it.
And Mike (Newell - director) was fantastic because he was pushing me further and further with his direction he was really keen on pushing me far as he possibly could.
Of course the other part of the film, apart from all the terror and suspense was the romance, how was that?
It was great. It was really fun to do and we had Mike Newell directing us, who has directed arguably one of the greatest romantic comedies ever, so it was absolutely fantastic.
I think it what was quite good is that certain bits of the film are all so dark, that it's good to have bits to balance it out, like all the stuff with Cho Chang and the dribbling of the orange juice and all of those things.
How easy was it working with Katie, doing those kind of embarrassing scenes?
it wasn't particularly embarrassing, it was okay, it was just funny.
I mean she's beautiful so I didn't really have to act that much, it wasn't hard to act as if I was in love with her or anything because she's beautiful, it was really fun.
It wasn't so much embarrassing but there were a couple of awkward moments after certain scenes when we didn't know quite know what to say but, it was great.
What was it like working with Rupert and Emma again? You've known each other for five years now..
It's was fine, it was great. I think we know each other quite well now so when we get back on set it's like there hasn't been time in between, it's just another day really.
It's great working with them, particularly in this one with Rupert where me and Ron have a little sort of spat, that was really enjoyable.
You as Dan, how do find mixing your film life with the rest of your life? How easy is it to have a normal teenage life?
Well the main thing is, I don't read any of the stories that are written because I think then that's the moment I'd become warped. I value my sanity too much to read all that. It hasn't really affected me that much in terms of my actual life.
Obviously I'm aware that not all teenagers are going and doing all of these things, but you know to me, that has become normality. I get recognised on the street, but that's about the extent of it.
No big showbiz parties?
No, I don't think I'd be very good at them.
With this film, we're four in, so do you see yourself possibly doing all seven?
I'm definitely doing the fifth one, I start filming in February.
After that it is a long way away, but when I was reading the sixth book, I was sort of going there's some stuff in here I'd really love to do.
I was trying to read it in quite an impartial way, not having made any decisions yet, but certain bits, like the whole of the cave chapter, all of that would be really fun to do.
Did you get an advance copy?
Absolutely not. In a way I wouldn't want to because I sort of get to discover what happens along with the rest of the world.
Unfortunately someone did reveal to me what happens at the end.
I was in Australia when it came out and apparently someone had done a drive-by spoiler, where they drove past a bookshop where people were queueing which is horrible, but quite funny in a way.
Surely you don't go to a bookshop at midnight and buy a copy?
No, that would be a very, very unwise thing to do. We order our copy in advance so we get sent it on the day of release.
Was this film really that much bigger in scale to do?
It is bigger, but in a way you don't really feel that because one day you'll do a really big scene and then you'll do a string of low key scenes so by the time you get to the next big scene you've almost forgotten about the last one.
You only get a sense of how big and spectacular it really is when you get to see the finished film at the end.
Did JK Rowling come down to set this time?
No, not at all. I think she, and rightly, views the films as being very, very separate from the books and I think what's great is that she now trusts us to be faithful to the books.
I think she always gets sent a script and before we start filming Mike Newell and David Heyman (producer) and the writer Steve Kloves all have big meetings with her.
You're a massive music fan, did you have a lot of input in how the bands work there?
Well David Heyman did ask me to name bands I was really into, and who were really dancey as well. I said Franz Ferdinand, but then he went back and got Jarvis Cocker. I mean Franz Ferdinand are fantastic but Jarvis Cocker, that was a real moment for me, meeting him.
And also two of the guys out of Radiohead, that was fantastic to meet them as well because I'm a huge fan of them.