Mark O'Neill

Mark O'Neill may refer to:

• Mark O'Neill (rugby league) (born 1975), Australian rugby league footballer of the 1990s and 2000s
• Mark A. O'Neill (born 1959), British entomologist and computer scientist
• Mark O'Neill (TV personality) (born 1984), Irish television personality and producer
• Mark O'Neill (cricketer) (born 1959), Australian cricketer