The actress, who is best known for portraying Sarah Jane Smith in Doctor Who and The Sarah Jane Adventures, died this morning. She had been suffering from cancer.
Sladen first appeared as Sarah Jane in the long-running BBC sci-fi alongside the Third Doctor Jon Pertwee, and went on to star with Tom Baker and David Tennant. She was given her own spinoff series, The Sarah Jane Adventures, in 2007.
Doctor Who Magazine originally tweeted: "With great sadness, DWM must report the loss of our beloved Sarah Jane, actress Elisabeth Sladen. The best of best friends. Too, too sad."
Sarah Jane Adventures creator and former Doctor Who lead writer Russell T Davies 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."
Current Doctor Who head writer Steven Moffat added: "'Never meet your heroes,' wise people say. They weren't thinking of Lis Sladen. Sarah Jane Smith was everybody's hero when I was younger, and as brave and funny and brilliant as people only ever are in stories.
"But many years later, when I met the real Sarah-Jane - Lis Sladen herself - she was exactly as any child ever have wanted her to be. Kind and gentle and clever; and a ferociously talented actress, of course, but in that perfectly English unassuming way."
Sladen leaves behind her husband, actor Brian Miller, and her daughter Sadie.
> Obituary: Elisabeth Sladen
> Gallery: Elisabeth Sladen 1948-2011
> Reaction: Elisabeth Sladen 1948-2011
> Read our 2006 interview with Elisabeth Sladen
> Read our 2008 interview with Elisabeth Sladen
> Read our 2009 interview with Elisabeth Sladen
Watch a classic clip of Elisabeth Sladen as Sarah Jane Smith in Doctor Who below: