Mark O'Brien (born 13 May 1984 in Dublin, Ireland), is an Irish footballer who currently plays for Dundalk in the League of Ireland Premier Division.
O'Brien is a central midfielder and comes from a footballing background as his father Derek played for Shamrock Rovers from 1981 to 1983 and his uncles Fran and Ray both played for Ireland.
His younger brother Colin played alongside him at Shelbourne.