Cillian O'Sullivan

Cillian O'Sullivan (born 1989 or 1990)^[1] is an American-born Irish actor who has had roles in Then You Run (Sky 2023),^[2] In From the Cold (Netflix 2022),^[3] Bull (CBS 2019),^[4] Vikings (History 2016),^[5] 6Degrees (BBC 2012),^[6] Single-Handed (RTÉ 2009),^[7] and Seacht (BBC/TG4 2008).^[8]

Born in New York to Irish parents,^[1] O'Sullivan's family moved back to Ireland when he was a child, and he attended school in Ballinlough, Cork.^[9] From an Irish-speaking family,^[1] his first television roles were in Irish language productions for TG4.^[8] After roles in several BBC productions,^[8] and playing Bobby Storey in the 2017 film Maze,^[1] O'Sullivan moved to the US, obtaining recurring roles in NBC and Netflix series.^[5][9] Misty Button, in which he had a lead role,^[10] won the "best narrative feature" at the 2019 San Luis Obispo International Film Festival.^[11]

In 2021, he filmed a Sky Studios series titled Then You Run,^[9][12] which was released in July 2023.^[2] As of 2022, O'Sullivan was reportedly working on a film titled The Lost Princess.^[13]

In 2025, O'Sullivan appeared as Devlin, an Irish gangster, in Daredevil: Born Again,^[14][15] and as Dr. Roger Korby in the third season of Star Trek: Strange New Worlds.^[16]