Here's a good list of the famous people who appeared as characters in the original show: Quantum Leap: Every Historical Figure Sam Beckett Encountered
Most of the ones where the celebrity was a significant character in the episode were after the Season 5 premiere featuring Sam leaping into Oswald. In the earlier seasons, those appearances were more incidental scenes in the larger story of the episode.
One of the things I liked about Quantum Leap originally was that it featured small personal stories for those characters and they weren't famous world-altering events. They lost me (and presumably many others) when they changed that and started doing the leaps with more famous characters.
Most of the ones where the celebrity was a significant character in the episode were after the Season 5 premiere featuring Sam leaping into Oswald. In the earlier seasons, those appearances were more incidental scenes in the larger story of the episode.
One of the things I liked about Quantum Leap originally was that it featured small personal stories for those characters and they weren't famous world-altering events. They lost me (and presumably many others) when they changed that and started doing the leaps with more famous characters.
