Oona O’Brien was born in Evanston, Illinois, on September 15, 2006, so when she debuted on Cobra Kai in Season 4, she was still in her early teens. She is currently a 19-year-old student at Brown University with over 580,000 Instagram followers and three seasons of one of Netflix’s most popular shows under her belt. For someone who had virtually no on-screen credits prior to landing a recurring role on a show with an established, vocal fan base, that is a fairly condensed timeline.
Prior to Cobra Kai, O’Brien’s acting career was primarily in theater, including a virtual production during the pandemic years, and commercials, such as American Girl and Nickelodeon. Before Devon Lee, she had only appeared in a short film called Sky High, where she portrayed Mia Savage. The casting of Devon Lee is somewhat noteworthy because it’s the kind of early resume that’s easy to ignore. She wasn’t an actress with a long list of credits or a skilled martial artist. She was an Illinois adolescent who was obviously capable of making a big impression.
When people investigate Oona O’Brien’s past, her father is one aspect that frequently comes to light. Ed O’Brien is the guitarist for Radiohead, a group that has produced some of the most highly regarded rock albums of the past thirty years, depending on who you ask. It appears that Oona was born during her father’s six-week tour of the United States.
It’s the kind of origin story that seems a little too dramatic to be true, but it is. Although O’Brien hasn’t talked much about how much it influenced her path toward acting, growing up with that specific family background likely meant exposure to creative environments early on.
Salvador is her older brother, and Susan Kobrin is her mother. Although O’Brien has established herself sufficiently on her own that the Radiohead connection reads more as intriguing background than as an explanation for her career, the family connection to the arts appears to be genuine. Rather than through industry connections, she obtained the Devon Lee role through traditional means, such as auditions and representation through the Osbrink Agency.
O’Brien had to start learning karate from the ground up for the Devon Lee role, which developed over the course of three seasons. According to her own account, she kicked male cast members in the groin in quick succession in her first filmed scene, which isn’t the most traditional way to start a long-running series. She continued to make appearances in 21 episodes over the course of Seasons 4, 5, and 6. She also made an appearance in the show’s last episode and concluded the series as one of its more talked-about younger characters.
From the outside, it’s fascinating to watch someone manage that level of public exposure while also enrolling in college. Throughout the release of the final season, she posted frequently, engaging with fans, making appearances on the podcasts of her co-stars, and sharing intimate rather than staged moments from filming.
During the release of Season 6, her Instagram following increased significantly, reaching over 580,000 as of early 2025. That’s a good starting point for a 19-year-old whose most notable accomplishment is a recently concluded show. It’s genuinely unclear what she will do next, but it seems like Devon Lee was more of a beginning than an end.
