Alias is about a spy named "Sydney Bristow" (played by Jennifer Garner) who thinks she's working for the CIA, but it turns out she's really working for an evil organization called SD-6, which is run by a man named "Arvin Sloane" (played by Ron Rifkin). Sydney discovers that Sloane is responsible for killing her fiance, and vows to take him and his organization down. She partners with her father Jack (played by Victor Garber), and coordinates with the real CIA, under the guidance of a handler named "Michael Vaughn" (played by Michael Vartan. In Season 2, Sydney succeeds in taking down SD-6. Things get complicated when Sydney's mother, Irinia Derevko, a former KGB agent in league with Sloane, comes back into the picture. To make matters worse, it turns out that Sydney's roommate has been killed and replaced by an imposter. The two fight and Sydney gets knocked out, only to awaken two years later in Hong Kong. Sydney investigates her lost time, and also learns more about the mysterious (and sometimes supernatural) character named Milo Rambaldi, who Sloane becomes more and more obsessed with. Through the course of the series, Bristow learns that she and her family's destiny is entwined with the prophecies of Milo Rambaldi, and she acts to stop the evil forces who are trying to exploit Rambaldi's power.

1. Jennifer Garner as Sydney Bristow
2. Ron Rifkin as Arvin Sloane
3. Michael Vartan as Michael Vaughn
4. Victor Garber as Jack Bristow
5. Carl Lumbly as Marcus Dixon
6. Kevin Weisman as Marshall Flinkman
7. Lena Olin as Irina Derevko
8. Melissa George as Lauren Reed
9. Greg Grunberg as Eric Weiss
10. Bradley Cooper as Will Tippin
11. Merrin Dungey as Francie Calfo
12. David Anders as Julian Sark
13. Mia Maestro as Nadia Santos
14. Rachel Nichols as Rachel Gibson
15. Elodie Bouchez as Renee Rienne
16. Balthazar Getty as Thomas Grace
17. Amy Acker as Kelly Peyton