On season four of 24 she played the new head of CTU Erin Driscoll, who fires Jack Bauer (Kiefer Sutherland) because of the heroin addiction he was forced to endure to maintain his cover, until - like all CTU bosses eventually do - she needs him back and reinstates him.
In the Canadian series La Femme Nikita she played Madeline, the second in command of the similarly tasked anti terrorism unit Section One, except ironically this character was would never have fired Jack Bauer as she employed the same 'any means necessary' approach to combating terrorists.
Watson then went on to play senator Madeline Pierce in the US reboot of the TV series, Nikita, where her character name was a nod to the role she originally made famous.
It was was shooting the second season of La Femme Nikita in 1998 that the actress, who full name was Faith Susan Alberta Watson, was first diagnosed with lymphoma.
While undergoing chemotherapy, the show's producers wrote around her limited time, and she was forced to wear wigs after losing all her hair. But she returned to the show proper in season three with her character Madeline sporting a new short hairstyle.
Throughout her lengthy career she received two Genie Award nominations for Best Actress - the Canadian equivalent to the Oscars - for 1978's In Praise Of Older Women, and 1996's Shoemaker.
She also played a mother who has an incestuous relationship with her son in one of David O Russell's first feature-length film Spanking The Monkey.
The role was reportedly tuned down by Susan Sarandon, Jessica Lange and Faye Dunaway, but Watson said she relished the challenge, knowing she didn't have a star name to protect.
- Daily Mail