b. 1970, Cork, Eire. While studying architecture, O’Leary was drawn into music. He had taken up the guitar and was soon an eager student, eventually advancing his studies at Musicians Institute in Los Angeles, California. After becoming a professional musician, his virtuoso technique attracted much attention and he soon achieved distinction in the related fields of contemporary jazz and improvised music as well as making a mark playing Scandinavian folk music.
Among artists with whom O’Leary has worked and sometimes recorded, mainly for Leo Records, are pianists Paul Bley, Uri Caine, Matthew Shipp and Bobo Stenson, bass players Palle Danielsson, Anders Jormin and Steve Swallow, drummers Joey Baron, Han Bennink, Bill Bruford, Jack DeJohnette, Peter Erskine, Pierre Favre, Billy Hart, Günter Müller, Sunny Murray, Ben Perowsky and Randy Peterson, violinist Mat Maneri, trumpeter Kenny Wheeler and multi-instrumentalist Tomasz Stanko.