WATCH: Elisabeth Sladen's career highlights
The star of The Sarah Jane Adventures Elisabeth Sladen has died of cancer aged 63.
Elisabeth rose to fame playing Sarah Jane in Doctor Who back in the 1970s.
In 2007, she was given her own series and it's become one of the biggest shows on children's TV.
Stars have been paying tribute to the popular actress.
Doctor Who star David Tennant
David Tennant talks about Elisabeth Sladen
David Tennant starred as the Doctor in three series of the show. He said: "When I was a kid I watched her in Doctor Who. To then be on Doctor Who working with Sarah Jane was a huge joy for me.
"Lis was lovely to be around and such a treat to work with. The sense that she's gone is very hard to compute."
Doctor Who star Matt Smith
Matt Smith, who plays the current Doctor, said: "What struck me about Lis was her grace.
"She welcomed me, educated me and delighted me with her tales and adventures on Doctor Who."
Blue Peter's Barney Harwood
Watch Barney talk about his memories
Barney worked with Elisabeth and said: "She had a personality that just takes over. It's just nice to work with people like that because you learn so much from them.
"She was amazing. Anything she did you wanted to be involved with."
CBBC's Chris Johnson
Watch Chris talk about his memories
CBBC presenter Chris Johnson said: "She's left behind so many fantastic stories, she'll never really leave us. Working with her was a dream come true.
"It's upsetting. The Tardis has got a little bit smaller today."
Sarah Jane Adventure's creator Russell T Davies
Russell T Davies, Doctor Who writer and creator of The Sarah Jane Adventures, said: "I absolutely loved Lis. She was funny and cheeky and clever and just simply wonderful.
"The universe was lucky to have Sarah Jane Smith. The world was lucky to have Lis."