Callaghan has made a name for himself in Liverpool as a construction magnate, but this success has perhaps been acquired by dubious means. The only thing dodgier than his practices in the boardroom would be those in the bedroom.
Prior to working on Three And Out, Gary played the role of Hrothgar in the 2006 film adaptation of the popular fantasy novel ERAGON. He has also recently appeared in Christian Carion's war drama JOYEUX NOËL, and Ken Loach's AE FOND KISS.
On the small screen, Gary has recently featured in PRIME SUSPECT: THE FINAL ACT and REBUS.
In 2002 Gary co-starred in Martin Scorsese's GANGS OF NEW YORK with Daniel Day Lewis and Leonardo Di Caprio, which followed closely on his breakthrough in the international hit, BILLY ELLIOT. For this role Gary received a BAFTA nomination for Best Performance by an Actor in a Supporting Role and a nomination for British Actor of the Year from the London Critics Circle Film Awards.
Throughout the 1990s, Gary co-starred alongside prominent actors in various critically-acclaimed films. These include CARLA'S SONG with Robert Carlyle and MY NAME IS JOE with Peter Mullan. The latter film marked the beginning of Gary's collaborations with Ken Loach.
His film debut was in the 1991 film, SHALLOW GRAVE, with Ewan McGregor and Christopher Eccleston.
Gary was born and raised in Glasgow. After performing in amateur theatre productions he decided to pursue acting professionally at the age of 32, joining Robert Carlyle's Raindog Theatre.