Brother of actress Fionnuala Murphy.
He uses the surname of Gillen because someone else was already registered as Aidan Murphy in the Actors' Guild. Gillen is his mother's surname.
Echoing his earlier work 14 years previous in John Michael McDonagh's short film "Second Death", Aiden Gillen repeats his exaggerated and threatening karate-moves in a similar bar scene toward Brendan Gleeson in Calvary - also by John Michael McDonagh.
Was nominated for Broadway's 2004 Tony Award as Best Actor (Featured Role - Play) for a revival of Harold Pinter's "The Caretaker."
Moved back to Ireland in 2009 with his wife and two kids, daughter Berry and son Joe. Now lives in Kerry, Ireland. .