Her agent, Pam Winter, said Watson died Saturday in Toronto after a long battle with cancer.
Watson was best known for her role on "24" as special agent Erin Driscoll during the Fox series' 2004-05 season.
More recently, she appeared on the CW series "Nikita" as well as on its earlier version, "La Femme Nikita," on USA.
Her films included "Hackers" and "Hedwig and the Angry Inch." TV guest roles included "Hill Street Blues, "Law & Order" and "The Equalizer.