Liam Dearg Ó Mainnín

Liam Dearg Ó Mainnín was an Irish criminal and murderer who flourished circa 1820's/1830's.

Ó Mainnín lived on an island on Loch an Ghadai in Derrycunlagh, Connemara. He was a confederate of the inhabitants of Teach Leath Bhealaigh, who "are said to have committed many murders at some period before the Famine" (2006, p. 42). Their names are given as Anna Mór Ní Chonghaile, her sister Kathsha, brothers Columb and Breen Dharag.

"It was on this island that Liam Dearg, the thief, used to live, and he had a small boat to come in and out. He used to watch the road until he'd see someone coming alone from Clifden or going there. If he failed to get a hold of someone going west he would get a hold of them going east, and he would take their money from them or the goods they had bought. At that time no respectable woman would go that way without two or three people to accompany her, for fear of Liam Dearg." (2006, pp. 42–43)

He is said to have disposed of the corpses in the lake.

Ó Mainnín was murdered by a fellow-thief, Sean na gCannai Ó Labhraí.