Doctor Who actress Elisabeth Sladen has died of cancer at the age of 63, the BBC has confirmed.
She joined the programme in 1973 and became one of the most popular companions in her role as Sarah Jane Smith. In 2007 she was given her own spin-off series, The Sarah Jane Adventures, which introduced her to a new generation of fans.
Tributes have been pouring in for the Liverpool-born actress, known to her friends and family as Lis.
Russell T Davies, creator of The Sarah Jane Adventures, which won this year's RTS Award for best children's drama, said all those involved in the series had been left "reeling" at news of her death.
He 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."
Sladen starred in Doctor Who alongside Jon Pertwee, the third doctor, and his successor Tom Baker.
She then returned to the series on a number of occasions over the years before her own CBBC show was created, in which she starred as an investigative journalist trying to defend Earth from extraterrestrial threats.
It had not been widely known that she had been suffering from ill health. She leaves behind her husband, the actor Brian Miller, and daughter Sadie.
Doctor Who lead writer and executive producer Steven Moffat said she was a "ferociously talented actress".