Reginald Leo McKern (March 16, 1920 - July 23, 2002), better known simply as Leo McKern, was an Australian actor who appeared in numerous British television programs, movies and in over 200 stage roles.

Some notable roles:

• Horace Rumpole in the TV series Rumpole of the Bailey
• Number Two in the TV series The Prisoner (there were several Number Twos; the one played by McKern appeared in three episodes including the final two)
• Ryan in the film Ryan's Daughter
• Thomas Cromwell in the film, A Man for All Seasons (1966)
• The murderous holy man in the Beatles' movie Help
• The Prime Minister in The Mouse that Roared
• Imperius, the reclusive priest in Ladyhawke
• Several roles in the late 1950s television version of The Adventures of Robin Hood (which starred Richard Greene as Robin)
• A scientist in the film X the Unknown
• Cardinal Leone in the 1968 film The Shoes of the Fisherman.