|The O.C. character|
Willa Holland as Kaitlin Cooper
|Last appearance||"The End's Not Near, It's Here"
|Created by||Josh Schwartz|
|Portrayed by||Shailene Woodley
(seasons three and four)
|Nickname(s)||Mini Coop / Mini Cooper
Squirt, Peanut (both by Gordon Bullitt)
|Occupation||High school student
(at the Harbor School; graduated)
|Family||James "Jimmy" Cooper
(older sister; deceased)
|Residence||Newport Beach, California
Kaitlin is the younger sister of Marissa Cooper and daughter of Jimmy and Julie Cooper. Occasionally seen during the first season, she is most interested in horseback riding on her pony, China. Kaitlin's life is eventually disrupted due to her father's embezzlement of clients' funds and the subsequent collapse of her parents' marriage. Julie tells Jimmy that she is relieved that Kaitlin is going to boarding school. Kaitlin does not feature in the season after that.
Kaitlin continues life at boarding school until the mid-winter break, when she comes back to Newport. The house of her childhood, however, is no longer her home but that of a man of Persian descent. Mail for the Coopers has been redirected to the Cohens' house next door. Kaitlin, now 14, follows the lead in search of answers, meeting Ryan Atwood at the door. At first, Ryan does not recognize the visitor. The circumstances of Kaitlin's arrival are questionable, as a former acquaintance of hers searches for Kaitlin and money she apparently stole. Though removed from the struggles of the rest of her family for some time (and mostly unaware, due to their lack of communication with her), Kaitlin seems to be no stranger to cover-ups. She is shown to have some of the same personality tendencies as her scheming mother, but the extent of Kaitlin's plotting is less certain. At the same time, Kaitlin develops a relationship with Johnny Harper, a surfer who was recently in love with her sister, Marissa. The two of them are drinking one night at the beach, resulting in Johnny's death as he climbs a cliff and falls to his death. After resolving the above issues, she returns home again, this time claiming she wants to see her sister's graduation. Before the graduation, she's shown to have other motives. Claiming that her sister's reign as the ruler of Harbor is over, she is staying home for good.
Kaitlin becomes a main character in season 4. When the season premieres, she is seen smoking marijuana, blackmailing Dr. Roberts, and acting apathetic about the death of her sister. She is usually in the company of the two brothers of Luke Ward: Brad and Eric. Other than those two, she does not seem to have any other friends in Newport Beach. Julie is called in to see the Dean of Discipline at Harbor School and realizes that Kaitlin has been flirting with one of her teachers and showing bad behavior. Thus, Julie and Kaitlin are asked to help with a clothing drive for people in Darfur. They grow even further apart, and Kaitlin starts lying. Eventually, it is discovered that Kaitlin, Brad, and Eric are stealing clothes from the clothing drive and selling them. This causes Julie and Kaitlin to fight, just after Julie thinks she and Kaitlin have rekindled their relationship. Kaitlin is attracted to band geek Will (played by famous singer and rapper Chris Brown) but after being accused of making fun of Will's personality by a rival band member, she is dumped by him. She grows attached to Gordon Bullit, a man who is trying to date her mother, Julie. She convinces Bullit that Julie likes him. While he is away, Kaitlin emails Bullit pretending to be her mother. When he comes back, Kaitlin finds out that Bullit is going to propose to her mother. She tries to tell them about the emails, but it is too late. Bullit proposes. Julie says no, but she will date him as she can see how attached Bullit and Kaitlin are. Later, it becomes clear that Julie is seeing Ryan's father, Frank Atwood. When Kaitlin finds out, she tries to stop the relationship. In "The Case of the Franks", it becomes clear the Frank has strong feelings for Julie. Ryan and Taylor become "Team Frank," and Kaitlin is "Team Bullit". Kaitlin tells Bullit to play the money card. Ryan tells Frank to play the romance card. Bullit buys Julie earrings, but Kaitlin tells him she wants "out of the box thinking." Kaitlin and Bullit come up with a plan to take Julie on Bullit's private jet, allowing Julie to choose anywhere in the world she wants to go.
Although Ryan and Taylor try to help Frank win Julie, she rejects his proposal. She only has one daughter left, and that daughter loves Bullit even though Julie doesn't. However, Kaitlin realizes that her mother doesn't want to fly away with Bullit. Kaitlin and Bullit agree to continue to be friends anyway. In "The Shake Up", Kaitlin does everything in her power to separate Frank and Julie, trying to frame him for liking clown porn by placing a large amount of it in his backpack when he is not looking. She also places posters of Frank's police mugshot around Newport with the words "This man loves clown porn" written on it. Julie confronts Kaitlin, who explains that she has nothing against Frank, but she feels he will leave their life as quickly as everybody else did in the past year. She confesses to Ryan that she actually has nothing against his father but she fears her mother is jumping into another relationship too soon and fears that their family is breaking apart. Julie and Kaitlin agree that Frank won't be going away, but they will spend some time as a family for a while; Ryan consoles her saying that he "will always be your brother, in a completely non-creepy way" regardless of whether their parents marry or not. Soon after an earthquake hits, they run into an ice cream shop for safety. Soon after, Kaitlin, realizes that the ice cream boy, Gary, has a huge crush on her. In "The End's Not Near, It's Here", Kaitlin and a pregnant Julie are finally on their own. She eventually gets a half brother Cooper, who is also the half brother of Trey and Ryan Atwood, although Ryan once quipped that he was her "brother in a completely non-creepy way". At the end of this final episode, a reformed Kaitlin is shown five years down the line, excelling as a Williams College student.
- Kaitin's age is a subject of dispute between fans (due to inconsistencies with the writing of the character), as in Season 1, Seth states she is in fifth grade, which, by the time of Season 3, would make her 13. However, it is stated in Season 3 that she is 14 turning 15, and that she was 11 the last time we saw her in Season 1, which means she was entering 7th grade in the beginning of the first season and in season 3 is in 9th grde. She has last stated in the fourth season that she is fifteen, although she should have been sixteen as she celebrated her 15th birthday in January 2006, according to the episode The Pot Stirrer. She is also shown driving her own car by herself at a time where she was supposed to be only 15. In either case, Kaitlin was older on the show than Willa Holland was in real life. Holland didn't celebrate her 15th birthday until after the third season concluded.
- Start up: The Sister Act (3.12) (before)
- Broke up: The Sister Act (3.12)
- Reason:Kaitlin stole money from his brother and left town
- Johnny Harper
- First Relationship:
- Start up: The Sister Act (3.12)
- Broke up: The Pot Stirrer (3.13)
- Reason: Johnny broke up with her because of their age difference but still wanted to hang out as friends
- Second Relationship:
- Start up: The Pot Stirrer (3.13)
- Broke up: The Cliffhanger (3.14)
- Reason: He's still in love with Marissa, and he falls off a cliff and dies
- First Relationship:
- Will Tutt
- Start up: The French Connection (4.10)
- Broke up: The Dream Lover (4.11)
- Reason: Kaitlin breaks up with him because they are so different