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.