Elisabeth Sladen Obituary

Actor whose role with Doctor Who brought her new audiences through The Sarah Jane Adventures

Elisabeth Sladen as Sarah Jane Smith with Jon Pertwee in the Doctor Who story The Time Warrior, 1973-74. Photograph: BBC Pictures Archives

The actor Elisabeth Sladen, who has died aged 65 of cancer, was for many a favourite companion of BBC television's great time traveller,Doctor Who. But though her character, Sarah Jane Smith, was much missed when her three years of voyaging in the Tardis came to an end in 1976, there was still more to come.

An inquisitive, independent, feminist journalist, Sarah Jane provided a somewhat bolder sidekick than previously. The producer Barry Letts had seen hundreds of candidates for the part: many had shown the necessary vulnerability, and others bravery, but only Sladen displayed both. When Russell T Davies revived Doctor Who in 2005, he wanted to show Billie Piper's character, Rose, that she was not the only person to have travelled with the Doctor, and it was Sladen he turned to. Working with her proved so enjoyable that he conceived a spin-off, The Sarah Jane Adventures, which has run for four series since 2007, seen initially on CBBC, with three more stories yet to be shown.

Born in Liverpool, Sladen attended drama and dancing courses at theElliott-Clarke school from an early age, making an appearance with the Royal Ballet, and performing as an extra in the 1965 film Ferry Cross the Mersey. She became an assistant stage manager for the Liverpool Playhouse repertory company, where she met the actor Brian Miller, and in 1968 they married.

Repertory company work in Manchester – notably as Desdemona in Othello – and Liverpool was followed by two seasons working for Alan Ayckbourn in Scarborough. When Miller got a West End job, the couple settled in London, and in the early 1970s, after six episodes as Len Fairclough's barmaid girlfriend in Coronation Street, Sladen obtained television roles in Special Branch, Public Eye, Doomwatch, Some Mothers Do 'Ave 'Em and Z-Cars. Her professionalism and versatility in the latter led to a recommendation to Letts, for whom she provided stability when Jon Pertwee handed over the role of the Doctor to Tom Baker. It was a daunting time for the newcomer, and he greatly appreciated her kindness.

When the moment came for her to leave the programme, she did so in an impressively underplayed scene of suppressed emotion with Baker. Work continued, in the drama Send in the Girls (1978, appearing opposite Miller), in comedies – Take My Wife (1979) and In Loving Memory (1980) – and in the classic serials Gulliver In Lilliput (1982, as Lady Flimnap) and Alice in Wonderland (1986, as Dormouse), both for Letts at the BBC. She also presented 98 episodes of the children's series Stepping Stones (1978-79) for Yorkshire TV.

Her return to the Doctor Who cosmos came in 1981, when the popular robot dog K-9 was given his own pilot programme, K-9 and Company, and so needed Sarah Jane as a human lead. Despite good ratings, the show was not taken further, but Sladen was soon reunited with Pertwee for Doctor Who's 20th anniversary story, The Five Doctors, a pair of Radio 2 drama series (1993 and 1996), and the Children in Need special, Dimensions in Time (1993). She also had roles in The Bill (1989), Men of the World (1994) and four episodes of Peak Practice (1996), observing good-humouredly that the fans who watched her as children were now working in the industry and giving her jobs.

The firm Big Finish's series of audio stories for Sarah Jane, released on CD and via online download, gave her a way of sustaining the character. Then Davies asked her to appear in the television series' successful revival. Proprietorial of Sarah Jane, Sladen was reluctant to return for what she suspected would be a jokey, fleeting cameo, and was pleasurably surprised to discover that she would be the guest lead in the episode School Reunion (2006).

Sladen once again displayed the pluckiness and vulnerability that had made her so popular, and Davies came up with The Sarah Jane Adventures. For four series she did battle with teatime-friendly aliens alongside her teenage sidekicks, including a cloned alien boy genius she adopted as her son. The series was a huge success, and latterly was graced with cameos from the later Doctors David Tennant and Matt Smith, and, in his final TV appearance, Nicholas Courtney, another favourite as the imperturbable Brigadier Lethbridge-Stewart. In the parent series, Sladen joined Tennant for the 2008 finale and his departure from the role on 1 January 2010.

Sladen was a popular convention guest and contributor to the enhanced versions of programmes that appeared on DVD. When she learned that Letts was very ill, she persuaded the producers to reunite her with him for the commentary on his favourite story, Planet of Spiders, which had been Pertwee's swansong and also featured Courtney.

She is survived by Brian and their daughter, Sadie.

• Elisabeth Sladen (Elisabeth Claira Heath-Sladen), actor, born 1 February 1946; died 19 April 2011

• This article was amended on 21 April 2011. The original did not give her name at birth in full, and said that she was born in 1948, making her age at death 63. These points have been corrected.