Having relocated to Los Angeles in 2002, Glau's first television credit was a guest role as a ballerina on the 2002 episode "Waiting in the Wings" (episode 3x13) of the television series Angel. There she caught the eye of director Joss Whedon, who later cast her in his short-lived TV series Firefly as River Tam, a role she reprised for the show's feature film sequel, Serenity.
Glau appeared on the episode "Love Conquers Al" (1x06) of the TV series Cold Case. She had a small role in the film Sleepover, in which she played a high school senior named Shelly. She also appeared in the CSI episode "What's Eating Gilbert Grissom?", and the second season of The Unit; portraying Crystal Burns, the girlfriend of Jeremy Erhart.
In 2006, Glau played Tess Doerner, a paranoid schizophrenic returnee in the second season premiere of The 4400 (episode "Wake-Up Call"), and became an essential recurring character from Season 3 onwards. Her character had the power to compel people to do whatever she wanted. She also starred in the science fiction film Mammoth.
Glau was cast in a TV movie on ABC Family called The Initiation of Sarah.
In Terminator: The Sarah Connor Chronicles, a series that debuted January 13, 2008, Glau plays the role of Cameron Phillips, a Terminator infiltration unit sent back to protect John Connor and Sarah Connor from Skynet. The seventh episode of the series, "The Demon Hand", included several scenes in which Glau (in character as Cameron) dances ballet.
In 2008, she was awarded another Saturn Award for her performance as Cameron Phillips in Terminator: The Sarah Connor Chronicles, and was nominated for the Spike TV Scream Awards in the category Best Actress in a Science Fiction Movie or TV Show for the same role.
| Year | Title | Role | Notes |
|---|---|---|---|
| 2002 | Angel | Prima Ballerina | Television episode "Waiting in the Wings" |
| Firefly | River Tam | Television series, star, 14 episodes | |
| 2003 | |||
| Cold Case | Paige Pratt | Television episode "Love Conquers Al" | |
| 2004 | Sleepover | Ticket Girl | Feature film |
| CSI: Crime Scene Investigation | Mandy Cooper | Television episode "What's Eating Gilbert Grissom?" | |
| 2005 | Serenity | River Tam | Feature film, star |
| 2006 | Mammoth | Jack | Television film |
| The Initiation of Sarah | Lindsey Goodwin | Television film | |
| 2006-2007 | The Unit | Crystal Burns | Television episodes: "Extreme Rendition", "Force Majeure", "Report by Exception", "The Broom Cupboard", "Johnny B. Good", "The Water is Wide ", "Outsiders" |
| The 4400 | Tess Doerner | Television episodes: "Wake Up Call", "The Ballad of Kevin and Tess", "Terrible Swift Sword", "Fifty-Fifty", "The Wrath of Graham", "Daddy's Little Girl", "Ghost in the Machine", "Tiny Machines" | |
| 2008-Present | Terminator: The Sarah Connor Chronicles | Cameron Phillips / Allison Young | Television series, star |