The Lieutenant of Inishmore /lɛfˈtɛnənt ... ˈɪnɪʃˌmoʊr/ is a black comedy by Martin McDonagh, in which the 'mad' leader of an Irish National Liberation Army splinter group discovers that his cat has been killed.

Irish National Liberation Army (INLA) man Mad Padraic is pulling out the toenails of Belfast drug dealer James, when he hears that his beloved cat, Wee Thomas, is poorly.

Padraic, a man considered too mad for the Irish Republican Army and sorely trying the patience of his INLA comrades, is intent on revenge.

The opening night cast included Jeff Binder, Andrew Connolly, Dashiell Eaves, Peter Gerety, Domhnall Gleeson, Brian d'Arcy James, Alison Pill, and David Wilmot.

An Australian production ran from 30 September to 18 October 2008, at the Sue Benner Theatre, Metro Arts in Brisbane, Queensland.