Mago (m)
A name used in the Kilrush and Dingle areas. It is now probably obsolete, but it appears to have been a form of Manus.

Morrin [Múireann] (f)
Meaning 'long-haired', this early Irish name has been anglicised as Marion or even Madge, a pet form of Margaret. Muirinn was an Irish language variant.

Riona [Rioghnach] (f)
This name may mean 'queenly', derived from rioghan, 'queen'. Regina was used to translate this name.

Roy [ruadh] (m)
Gaelic ruadh, 'red', unconnected with French roi, 'king'. It is becoming increasingly popular in Ireland.

From the Appletree Press title: Irish First Names.
Also from Appletree: Irish Family Names, A Little Book of Irish Family Names and the Book of Irish Names.