Matt Smith starred alongside Elisabeth Sladen last year as a special guest in a two-part episode of her Time Lord spin-off show "The Sarah Jane Adventures".
And the actor - the current incumbent of the "Doctor Who" role - has fond memories of his time working with Elisabeth Sladen.
Matt Smith says, "What struck me about Lis was her grace. She welcomed me, educated me, and delighted me with her tales and adventures on Doctor Who. And she also seemed to have a quality of youth that not many people retain as they go through life."
"Her grace and kindness will stay with me because she had such qualities in abundance and shared them freely... I will miss her, as will the world of Doctor Who and all the Doctors that had the good pleasure to work with Lis Elisabeth Sladen and travel the universe with Sarah Jane."
And Tom Baker, who appeared in the show with Elisabeth Sladen when he played the Doctor between 1974 and 1981, writes on his website, "Sarah Jane dead? No, impossible! Impossible... She can't be dead. But she is, she died yesterday morning. Cancer. I had no idea she was ill; she was so private, never wanted any fuss, and now, gone."
"A terrible blow to her friends and a shattering blow for all those fans of the programme whose lives were touched every Saturday evening by her lovely heroic character, Sarah-Jane Matt Smith... It is so consoling when one is sad and bereft to remember the good times, the laughter, the glamour."
"Those sweet memories of happy days with Lis Elisabeth Sladen, the lovely, witty, kind and so talented Lis Elisabeth Sladen. I am consoled by the memories. I was there, I knew her, she was good to me and I shall always be grateful, and I shall miss her."
Elisabeth Sladen died on Tuesday at the age of 63 after losing her battle against cancer.