Elisabeth Sladen first appeared on the cult sci-fi show in 1973 and she played Sarah Jane Smith, the sidekick of both Jon Pertwee and Tom Baker till 1976. She reprised the role many times in subsequent decades. Her character landed her a spin-off series, 'The Sarah Jane Adventures'.
A statement from Sarah Jane Adventures creator and 'Doctor Who' writer Russell T. Davies reads, “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."