Chloe O'Brian  Chloe O'Brian is a fictional character played by actress Mary Lynn Rajskub on the US television series "24". An analyst at CTU Los Angeles (and later New York), she is Jack Bauer's most trusted colleague, often doing unconventional and unauthorized favors for him, even at personal risk to herself. As O'Brian, Rajskub appeared in 137 episodes of "24", more than any other actor except series star Kiefer Sutherland, who appeared in all 204 episodes of the series. UGO.com named her one of the best TV nerds. AOL named her one of the 100 Most Memorable Female TV Characters. O'Brian is exceptionally intelligent; in particular she displays extraordinary mastery of computer science. Spending most of her time behind a computer terminal, she is rarely sent on field assignments; however, she has demonstrated proficiency with weapons in Day 4, 5, and 8. She works very well under pressure, yet it is obvious when she is under pressure, that she has always demonstrated a degree of social awkwardness. Despite her lack of social graces, Chloe has gained several friends at CTU and has shown to have a great deal of loyalty to them. She helped CTU Agent Chase Edmunds take care of his daughter from a previous relationship after the child's mother abandoned Chase and their child. She even tried to pass the child off as her own, so as to keep Chase's then-girlfriend, Kim Bauer, from knowing. Before the start of Day 6, she and Milo Pressman briefly dated. This was a source of hostility between Milo and Morris. Toward the end of Day 6, it is revealed that Chloe is pregnant with Morris's child. In interviews to promote the show's return to Fox with the miniseries, "", actor Kiefer Sutherland revealed that Rajskub would be reprising Chloe, but hinted that the relationship between her and Jack Bauer would be more adversarial than before. He also suggested that the reason for this was possibly related to her actions during the show's final season. Introduced in the third season of the series, Chloe O'Brian is a senior analyst at CTU. Her other experience at CTU includes Intelligence Agent and Internet Protocol Manager. She received her education at the University of California-Davis, having received her BSc in Computer Science. In "", it is revealed that before coming to CTU Los Angeles, she worked at CTU: Washington DC with Chase Edmunds. Chloe continues to work at CTU as an analyst.