Cillian O'Sullivan

Career overview

Cillian O'Sullivan was born on 28 September 1989 in New York, United States. He is described as an American‑born Irish actor and is also credited under the names Cillian O'Suilleabhain and Cillian Ó Súilleabháin. As of the latest available data he has accumulated seventeen acting credits across film and television, a record reflected in his profile on The Movie Database.

O'Sullivan’s television work includes appearances in a range of productions from the United Kingdom, Ireland and the United States. In 2012 he featured in the BBC series 6Degrees, and he later took a role in the Irish crime drama Single‑Handed. He appeared in the History channel’s historical drama Vikings in 2016, and in 2019 he was cast in the CBS legal series Bull. More recent credits include the Netflix spy thriller In From the Cold in 2022 and the Sky drama Then You Run in 2023.

Throughout his career O'Sullivan has worked across both American and European productions, demonstrating versatility in drama, historical epics and contemporary thrillers. His continued presence on major broadcasters such as BBC, History, CBS, Netflix and Sky reflects a steady engagement with high‑profile series. The breadth of his credited work, as recorded by industry databases, underscores his ongoing contribution to television acting.