Holden is also known for her roles as Adele Stanton in The Majestic (2001), Cybil Bennett in Silent Hill (2006), Olivia Murray in The Shield (2008), Renee in The Americans (2017–2018), and the Crimson Countess in Vought News Network: Seven on 7 with Cameron Coleman (2021) and The Boys (2022).

[citation needed] After graduating from the Bishop Strachan School, Holden attended McGill University, where she studied economics and political science.

[10] Early in her career, Holden made a name for herself by co-starring opposite Burt Reynolds in Physical Evidence (1989), Vanessa Redgrave in Young Catherine (1991), and William Shatner in the TV Movie TekWar: TekLab (1994).

After making various guest appearances on Due South, Murder, She Wrote, and Poltergeist: The Legacy (when she played a dual role), Holden found some success playing a recurring role on the seminal sci-fi series The X-Files: Marita Covarrubias, a mysterious government worker who becomes an informant to Special Agent Fox Mulder, from seasons four through nine (1996–2002).

Other movie roles have included those of Michael Chiklis' character's former love interest in Fantastic Four (2005), Cybil Bennett in Christophe Gans' artistic-horror video game adaptation of Silent Hill (2006),[12] Amanda Dumfries in The Mist (2007).

From 2010 to 2013, she played the role of Andrea, a civil rights attorney and survivor of a global zombie plague in The Walking Dead, an AMC television horror drama series.

[citation needed] Holden joined the cast of American legal drama television series Proven Innocent (which premiered in 2019 on Fox), where she plays Greta Bellows.

[citation needed] In 2022, she joins The Boys season 3, in the role of Crimson Countess, while also performing the songs "America's Son" and "Chimps Don't Cry".

Holden is a founding board member of the Canadian Somaly Mam Foundation,[21] which campaigns against human trafficking, and an advisory board member of the Somaly Mam Foundation in the U.S.[citation needed] In 2014, Holden worked with Operation Underground Railroad, a volunteer organization that aims to hunt down and arrest child sex traffickers.

[citation needed] She also won "The Look of The Year" Elite model search in Toronto and was nominated in 1996 for a Gemini Award for Best Performance by an Actress in a Guest Role in a Dramatic Series for Due South (1994).