Andrew Tiernan trained at the Drama Centre London. His earliest break came in 1991, when he was cast in Derek Jarman's Edward II (1991), at the same time he was cast as DC Rosper in the award winning television series Prime Suspect (1991), alongside Helen Mirren, Tom Bell and Tom Wilkinson. He then went on to play the stuttering psychopath Sean Kerrigan in Cracker (1993) with Robbie Coltrane in 1993 and he has continued to be cast in award winning productions. A recognizable face in television & feature films, Tiernan has become known as a solid character actor, with the ability to transform. Such examples are; Szalas in Roman Polanski's The Pianist (2002), and as the deformed hunchback; Ephialtes in Warner Brother's blockbuster 300 (2006), written by Frank Miller & directed by Zack Snyder. During his career he has worked with; Angelina Jolie, Adrien Brody, Antonio Banderas, Anthony Hopkins, Sam Neill, Timothy Hutton, David Duchovny, Rhys Ifans, Brad Pitt, Tom Cruise, Gerard Butler, Michael Fassbender, Robin Williams, John Turturro, and Jean-Marc Barr.