MacKenna is the English form of the Irish surname Mac Cionaoith. The Mac Cionaoith were originally based in Meath, but in early times were brought north into Clogher as hired fighters by the rulers of that territory, and quickly became lords in their own right of Truagh, a territory on the borders of the modern counties of Tyrone and Monaghan. Their power endured down to the seventeenth century, their last chief being Patrick McKenna, who died near Emyvale Co. Monaghan in 1616. Another branch of this family settled in Co. Down in the seventeenth century, near the town of Maghera.
The name is one of the few for which anglicisation, the loss of the "Mac" prefix, has never worked. The surname is still very numerous in the area of the original homeland, to the point where suffixes and local nicknames are necessary to identify the different families of the name. Over the centuries, however, has spread throughout the country.
In the century since Matheson’s survey of the frequency of Irish surnames, the McKennas appear to have gone forth and multiplied. Ranked 89th in 1890, with 201 births of the name, by 1996 they were at 68th in the Republic of Ireland and 52nd in Northern Ireland, based on telephone directory listings.
.Juan MacKenna (1771-1814) was born at Clogher in Co. Tyrone, educated in Barcelona and became Governor of Oserno in Chile. He became a general under the Liberator Bernardo O'Higgins in the fight for Chilean independence and was killed in a duel with one of O’Higgins’ opponents.
Siobhán McKenna (1921-86) was the most famous Irish actress of her generation, renowned for her parts in Shaw’s St. Joan and Murphy’s Bailegangaire.
T.P. McKenna (b. 1929), originally from Cavan, is also well-known on television, in films and on the stage of the Abbey.
Martin McKenna (1832-1907) emigrated to Australia in 1845 and set up the Campaspe Brewery. He became a respected politician and farmer.