Fergal O'Brien (born 8 March 1972) is an Irish professional snooker player.
A member of snooker's main tour since turning professional in 1991, O'Brien has been ranked within the world's top 64 players since 1994, reaching his highest position, 9th, for the 2000/2001 season.
He has won one ranking title - the 1999 British Open, where he defeated Anthony Hamilton 9–7 in the final - and reached two other major finals, notably in the 2001 Masters.