I guess I specifically meant Jim Morrison. Of course the Doors met each other, but what about the other possibilities contained therein?
Definitely. They were in the same music circles.
There are two stories of Janis Joplin and Jim Morrison meeting. In an interview in Bam Magazine, their mutual producer, Paul Rothschild claims to have introduced them at a party at his place. He thought they'd work well together. They didn't, Morrison got too drunk, which annoyed Joplin and she knocked him out with a bottle of Southern Comfort as he was trying to grab her by the hair after she got in her car. The problem with that story is that Paul says they never met again.
But, in a biography about Janis ^(1), there is a lengthy passage about their relationship and how they got together after the Monterey Pop Festival that feels slightly more amicable. In this version, they definitely had sex at a party at her apartment with Morrison cheating on his girlfriend at the time. It doesn't seem like the relationship lasted much longer then that, so you have to wonder it it really happened, did the knock episode happened before or after this.
Jimi and Jais met in 1967 at the Monterey Pop Festival and became good friends. They never performed together on stage. There is some speculation they were lovers, but nothing concrete. But they definitely partied together and frequently performed at the same venues on the same nights. They died a mere 16 days apart.
Morrison and Hendrix met at least twice. The first was at Steve Paul's Scene in NYC, on March 6th or 7th when Jim got on stage while Jimi was playing, sung a few lyrics, then passed out.^(2) (BTW, Janis was at this concert too.)
The same thing happened about a month later, but he didn't even make it on stage. This famous exchange happened there.
"Amid all the chaos, Jim Morrison tried to get on stage. British soul star Geno Washintong saw what happened next: 'The place was fuckin' packed, the people are going ape shit, Jim Morrison is drinking his drink and staggers up to the front of the stage, "Hey Jimi! Jimi! Let me come up and sing, man, and we'll do this shit together." So Jimi goes, "That's okay, fella, I can handle it myself." And he said, "Do you know who I am? I'm Jim Morrison of the Doors." "Yeah," said Jimi, "I know who you are—and I'm Jimi Hendrix.""
I'd be surprised to find that those were the only two times they met, but those are the only times documented.
1- Pearl – The Obsessions and Passions Of Janis Joplin