Stephen Hagan was raised in the village of Greenisland in County Antrim, Belfast, Ireland. He was born into a family that had an established property developing business and had possible career avenues in either that business or accounting. However, Stephen opted to pursue his passion for acting after a chance acting stint at the local Lyric Theatre in Belfast. Afterwards, he made his way to London to further study and pursue acting. During his final year of study in 2007, Stephen performed in Anthony Sher’s play, The Giant, performed at the Hampstead Theatre. In that same year, Stephen made his screen debut in the British drama Clapham Junction (2007). Two years later, Stephen appeared in the Steven Seagal actioner Against the Dark (2009). In television work, Stephen appeared on an episode of the British drama Mistresses (2008) and made recurring appearances on the drama short The Cut (2009) and Injustice (2011).