John Llewellyn

John Llewellyn may refer to:


 * John Llewellyn (fencer) (born 1957), British fencer who appeared at three Olympic Games
 * John Llewellyn (racing driver), British former auto racing driver
 * Sir John Llewellyn (academic), academic administrator in New Zealand and Great Britain
 * John Anthony Llewellyn (1933–2013), British-born American scientist and NASA astronaut
 * Sir John Dillwyn-Llewellyn, 1st Baronet (1836–1927), Welsh Conservative Member of Parliament
 * John Seys-Llewellyn (1912–2003), Welsh barrister and judge
 * John Llewellin, 1st Baron Llewellin (1893–1957), British army officer and politician