During visits to Galway in the summers, McDonagh became acquainted with the dialect of English spoken in western Ireland, which he would later put to work in his plays. His ironic combination of coarse country language, primal symbolism and black humour represents a peculiar fusion of the work of John Millington Synge with the modern drama of Harold Pinter, David Mamet and British television comedy.
He has been awarded Critics' Circle Theatre Awards for Most Promising Playwright in 1996.
His dramatic corpus to date incorporates two dark comedic trilogies, The Leenane Trilogy (The Beauty Queen of Leenane, A Skull in Connemara, The Lonesome West) and The Aran Islands Trilogy (The Cripple of Inishmaan, The Lieutenant of Inishmore, The Banshees of Inisheer), and the dark fantasy, The Pillowman, as well as two prize-winning radio plays, including The Tale of the Wolf and the Woodcutter.
The story of the dysfunctional relationship between a spinster and her domineering mother, during the course of which the former faces her last chance at love, and the latter faces a rather grim end. Nominated for Tony Award for Best Play in 1998.
A Connemara man has the job of smashing the skeletons in old graves, and his newest customer is the wife he killed years before, which may or may not have been accidental.
The insane leader of an IRA splinter group has just found out his best friend has been killed. The best friend is a cat... hilarity and/or violence ensues. Nominated for Tony Award for Best Play in 2006.
The finale of the Aran Islands trilogy. (unproduced and unpublished)
A writer in a non-specified totalitarian state is interrogated over the content of several of his dark-as-night, Brothers Grimm-style short stories. At first assuming he is being questioned over a perceived political subtext in his writing, he comes to find out that there have been a series of local child murders that seem to have been inspired by a few of his gruesome and imaginative stories. To add fuel to the fire, if he cannot prove his innocence he will be executed at the end of the night. Awarded Laurence Olivier Award for Best new play in 2004 and nominated for Tony Award for Best Play in 2005.
Six Shooter, which is the playwright's first move into film, features Brendan Gleeson, Ruaidhri Conroy, David Wilmot and Aisling O'Sullivan. The black comedy follows Gleeson as he makes a sad train journey home, just hours after his wife's death, but on the trip he encounters a strange and possibly psychotic young man. The short film was shot on location in Wicklow, Waterford and Rosslare.
After winning his Oscar for Six Shooter, McDonagh entered into an agreement with Focus Features to direct a feature-length film from his screenplay In Bruges, about two hit men who hide out in Bruges after a job gone wrong. Colin Farrell, Ralph Fiennes, and Brendan Gleeson star in the film, released in the USA in 2008. The film was also the Opening Night film for the 2008 Sundance Festival and the Jameson Dublin International Film Festival.