Mark O'Neill (born 19 June, 1975, in Paddington, New South Wales) is an Australian former professional rugby league player. He previously played for the Balmain Tigers and the Wests Tigers following the merger of Balmain and Western Suburbs Magpies; and Leeds Rhinos and Hull Kingston Rovers in the Super League. O'Neill's position of choice was at prop.
O'Neill was on the receiving end of a serious case of foul-play when Danny Williams of the Melbourne Storm punched O'Neill in the face in an off the ball incident. Williams received an 18 match ban.
At the end of the 2005 season, O'Neill moved to England and Leeds Rhinos. His season at Leeds was marred by injury. A pre-season friendly resulted in a shoulder injury which sidelined him for four months and a leg muscle tear resulted in six weeks off the field. O'Neill's contract at Leeds was not renewed and he spent 2007 at Hull Kingston Rovers where he played his final year in professional rugby league before retiring.