Chloe O'Brian on Day 8
|Portrayed by||Mary Lynn Rajskub|
|Seasons||3, 4, 5, 6, 7, 8|
|First appearance||Day 3: 1:00 PM – 2:00 PM|
Chloe O'Brian received her BSC in Computer Science from the University of California. Although she has wonderful computer and hardware skills, her social skills are lacking. She is often seen as sarcastic and hostile to others.
 Day 3
We first meet Chloe O'Brian at the beginning of Day 3. During Day 3, Chloe O'Brian helped successfully stop a computer virus released into CTU remotely by Nina Myers. She'd also hated to do tasks that would be considered highly unorthodox for Jack Bauer. Throughout the series, she has grown to trust Jack because he almost always produces results.
 Day 4
During Day 4, Chloe asks for Jack help when her friend is put into danger by terrorists. She realizes that it could be in connection with the train bombing that started the day. Despite warnings from Erin Driscoll, Chloe uses the sources of CTU to aid Jack (who at this point, did not work for CTU) in finding her friend. After Jack saves her friend, Driscoll fires Chloe for disobeying her. After Driscoll resigns from her post, Michelle Dessler pleads for Chloe to return to CTU. She agrees.
Chloe begins to develop a friendly relationship with Edgar Stiles, a co-worker. Although she sometimes gets annoyed with him, she knows that he is a nice guy. Later that day, Edgar is worried about Chloe when she goes out in the field. His worries proved to be justified as Chloe is attacked. Chloe is able to get a hold of gun and kills the terrorist who is attacking her. She is dumbfounded that she was able to kill someone.
 Day 5
At the beginning of Day 5, we learn that Chloe had a one night stand with Spenser Wolff. Later, she is hurt when she finds out that Spenser Wolff unknowingly gave vital information from CTU to the men behind Palmer's assassination. As she is going to work. She learns that Michelle Dessler and David Palmer have been killed and that Tony Almeida was severely injured. She realizes that everyone who knows that Jack Bauer is still alive is being killed. She calls Jack Bauer for help. Jack saves Chloe from being killed. In return, Chloe helps him break into Wayne Palmer's apartment in order to find out why David Palmer was killed. She helps to clear Jack for the murders of Michelle Dessler and David Palmer.
Later, Chloe works with other CTU staff members to overthrow the incompetent Lynn McGill. Soon after this, CTU is attacked by nerve gas. Chloe watches in horror as her friend Edgar Stiles is killed in front of her. Chloe slowly recovers in order to help save the remaining lives of workers in CTU. After this attack, Homeland Security comes to CTU to absorb it. Audrey Raines helps Chloe keep her job because she knows she will be vital to helping Jack Bauer bring down President Logan. Chloe is put into a detention center after it is revealed she has been helping Jack.
Eventually, Chloe escapes and makes her way to Bill Buchanan's house. They set up a makeshift CTU to help Jack. Later, Karen Hayes calls Buchanan to warn him that CTU is coming to look for Chloe. She is beginning to grow weary of President Logan. Chloe is able to flee the scene and help Jack from various locations. At one bar, she continually tasers a man who is annoying her while she works.
Chloe is able to help Jack get a recorded admission from Jack from President Logan. She gets help from her ex-husband Morris O'Brian. They become close, especially since Chloe is so distraught after Edgar's death. At the end of the day, Bill Buchanan hands her a photo of her and Edgar. Morris holds Chloe as they leave CTU.
 Day 6
During Day 6, Chloe is still working at CTU and now is sporting brown hair. It is soon revealed that she briefly dated Milo Pressman before getting back together with Morris O'Brian. The fling with Milo creates tension that Chloe tries to mediate. Chloe faces adversity early on when she learns of the plot to sacrifice Jack Bauer to end a series of terrorist attacks. With the help of Morris, she tries to save Jack's life. When the attempt almost destroys the entire operation, Chloe sadly realizes that Jack needs to be sacrificed in order to save lives.
Chloe is happy to learn that Jack survived the threat on his life and aids him in trying to stop his would-be-killer, Abu Fayed. Later, Morris is lured out of CTU on a false pretense and captured by Abu Fayed. Bill Buchanan relieves a distraught Chloe from her duties. Eventually, Chloe regains composure and is able to help locate Morris. Morris is brought back into CTU but enters a depression because he reprogrammed a detonator that could potentially allow Fayed to kill thousands of people. Chloe, fed up of Morris feeling bad for himself, convinces him to come back to work. She continues to keep tabs on Morris and begins to suspect that he's turned back to his old alcohol addiction. Chloe finally believes he is clean, but we see Morris emptying a whiskey bottle.
Later, Jack enlists Chloe to help him steal bomb schematics. Morris forces Chloe to report her behavior to Bill Buchanan who excludes Chloe from helping Jack because he doesn't trust her. Eventually, Buchanan brings Chloe back to the floor when he realizes he needs his best people. However, the rift between Morris and Chloe remains. Chloe chastises Morris for forcing her to tell Buchanan. In the midst of the argument, Chloe mentions how Morris armed the terrorists. She quickly apologizes but Morris decides to transfer out of Chloe's department and makes it clear that the relationship is over.
Chloe confronts Morris about their breakup. Morris tells her the relationship will never work because they can never forget his role in arming the terrorists. Soon after, CTU is invaded and the entire staff become hostages. CTU is able to regain control.
Near the end of the day, Chloe faints at her workstation. She is sent to medical. In the final hour, it is revealed that Chloe is pregnant with Morris's child. This revelation causes an ecstatic Morris to forget about their previous breakup.
 Day 7
- Chloe is the third longest running character on the series. She is third only to Jack Bauer (who has appeared in every episode since Day 1) and Tony Almeida.
- Chloe (with Mary Lynn Rajskub providing the voice) appeared in the 400th episode of The Simpsons, entitled "24 Minutes".
- The picture Bill handed over to Chloe, at the end of Day 5 which has her and Edgar smiling, has scribbled letters at the back. When unscrambled, it would read as "JACK IS DEAD" and "FAN PHONE".
- In 2007, The United States Department of Homeland Security announced Project Chloe, a program designed to maximize security via the use of unmanned drones patrolling above US Airports (Incidentally, unmanned drones play a part in Day 6). The project was dubbed Chloe because Secretary of Homeland Security Michael Chertoff's favorite television series is 24.