She played the role of Sarah Jane Smith, one of the Doctor’s assistants, and then had her own spin-off series recently, The Sarah Jane Adventures. She accompanied Doctors 3 & 4 (Jon Pertwee and Tom Baker) and showed up for appearances in the newest iteration of the show, opposite David Tennant and Matt Smith.
Many of my favourite older episodes are ones with Lis Sladen, and I can hardly imagine a Doctor Who series without her. Sarah Jane had a great deal of strength and I think she was one of the Doctor’s best companions.
I think this weekend I shall be re-watching some of my favourite episodes, in tribute to Lis Sladen.