Hailing from Weehawken, New Jersey, O'Brien grew up in an Irish-American family, attended Christian schools before becoming agnostic, and honed his craft at NYU’s Tisch School of the Arts after early stage work in high school. He later shifted to voice-over work, becoming known for anime roles such as Gaara in the Naruto series, Vincent Law in Ergo Proxy, and Kenzo Tenma in Monster, while also len…
