She was a regular on the short-lived television series Ferris Bueller which was a TV remake of the famous film Ferris Bueller's Day Off which she co-starred with a then unknown Jennifer Aniston. She also had major recurring roles on Picket Fences as Lydia Brock, as Barbara Norton on Grace Under Fire, and on Providence as Cynthia Blake. She also had recurring roles on Ellen as Susan, and on Charmed as Claire Pryce, in both shows' premiere seasons; both characters were the boss of the series lead's characters in their respective jobs.
She has had guest roles in various shows, including 7th Heaven, Life Goes On, Friends, Days of Our Lives, Passions, Party of Five, The Wonder Years, Matlock, Malcolm in the Middle, Ally McBeal, Murder, She Wrote, Boston Legal, Diagnosis: Murder, Nash Bridges, CSI: Crime Scene Investigation, NCIS, NCIS: Los Angeles, The Practice, L.A. Law, Chicago Hope, Crossing Jordan, ER, St. Elsewhere, Star Trek: The Next Generation, Gilmore Girls, Kate & Allie, Murphy Brown, Newhart, Growing Pains, How I Met Your Mother, Sabrina, the Teenage Witch, Clueless, Dharma and Greg, Life with Bonnie, The Nanny, The Jamie Foxx Show, The King of Queens, Two and a Half Men, Big Love, The Mentalist, Six Feet Under, and Charmed.
From 2006 to 2010, she played Angela Petrelli on the NBC series Heroes. In 2008, her role went from recurring to series regular. She will reprise her role in 2015 as part of the miniseries Heroes Reborn. As for her roles in movies as of 2009, she had a small role in the movie He's Just Not That into You and was one of the main supporting characters on the Disney Channel television movie Go Figure.