Political figure, Thomas J. Kelly, the Fenian activist, was born in Mountbellew in 1833. Having emigrated to America and fought in the Civil War there, and started organising for independence. He became Chief of Staff of the Irish Republican Brotherhood in Ireland and England.

In 1867, after a disorganised and betrayed campaign, he was picked up and while he and a companion were being driven to gaol in a black police van there was an attempt to rescue him, in the course of which one of the policemen guarding him was accidentally shot dead. Three men out of the crowd assailing the van were accused of this murder and died in 1908.

A plaque marks his birthplace in the Square.