This is what the original Ronald McDonald, played by Willard Scott, looked like in 1963:

This is what Ronald McDonald looked like in 1971, again played by Willard Scott:

This is what Ronald McDonald looked like in the 1980s and 90s, played by Squire Fridell (1984-1991), Jack Doepke (1990-1992), and Joe Maggard (1994-2007):

This is what Ronald McDonald looks like in Japan: