Before his roles in Easy Rider and Five Easy Pieces propelled him to perma-fame, actor/writer/director Jack Nicholson performed in two bit parts on The Andy Griffith Show. His first appearance was in 1966, as the husband of a woman who forgot her baby outside the Mayberry Sheriff’s Office, to have it discovered and rescued by Opie. (It’s season 7, episode 10, if you want to watch the whole thing on Netflix.)
 

 
Maybe this is just values dissonance at work, but no amount of suspension of disbelief in the world can get me past the idea of a ranking law enforcement officer simply handing an abandoned baby over to a strange couple just on their say-so—not even in ‘60s small-town America, and least of all when the claim they’ve laid on the child is a explicit admission of horrifying negligence.

His second appearance was a meatier part in 1967, around the time he began making serious turns toward the weird, writing the script for Roger Corman’s bizarre attempt at counterculture pandering The Trip and appearing in the drugsploitation oddity Psych-Out. But in Andy Griffith’s season 8’s episode 7, Aunt Bee is called to serve as a juror and finds herself recast as Henry Fonda from 12 Angry Men. Nicholson plays the defendant. I suspect there’s loads of potential in this episode for a mashup with A Few Good Men.