Cryowhite asked this question in another sub-forum about a week ago and it didn't get much of an answer.
Hello everybody! :D
Just here to ask you all some really fun question! :D
Which crossover is your #1 favorite? :D
Being the nit-picker I am, I decided the question really belonged in a different sub-forum. And I am taking the liberty answering it solely from a RPG view point.
As a long-time sufferer of Roy Thomas Syndrome, I have always utilized huge gobs of Creative Plagarism in my campaigns. I ran a storyline in a Dimension-hopping campaign involving an alternate universe with a Pulp-Era setting in which Doc Savage became a recurring NPC. I later had the Shadow and Oliver "Daddy" Warbucks appear.
I had a long-running Teenagers From Outer Space campaign that was made of this sort of thing. Nearly all the characters, whether PCs or NPCs, were lifted from other anime sources. Two of my players chose characters from the comic book NINJA HIGH SCHOOL. We had characters from RANMA 1/2, DIRTY PAIR, DR. SLUMP, and the Disney movie THE SHAGGY DOG. In one of the stranger sessions we crossed over with THE PRISONER.
Dimension-Hopping campaigns, such as GURPS: Infinite Worlds are perfect for this sort of thing. I once ran a convention one-shot in which several characters from different universes find themsevles on a mysterious island like the one in "Lost". I had Luke Skywalker, Agent J from "Men in Black", Kim Possible, Zoe from "Firefly", and Number 6, (yes, the Prisoner again). I also had made up character sheets for Sir Lancelot, Lt. Worf and Jessica Fletcher, but none of the players selected them.
Perhaps the most gratuitous and wacky cross-overs I did were in a **Champions **campaign based on JUSTICE LEAGUE INTERNATIONAL. I had the JLI face the "Misfits of Science", and Dr. Loveless from "The Wild, Wild West". I always wanted to have them do battle with the castaways from "Gilligan's Island" but I couldn't come up with a good excuse for them to get into a fight and because I figured my players would kill me.
In another Champions campaign involving supers in a near-future setting, I made up a character for a grown-up version of Jonny Quest. On a whim, I wrote on his character sheet that he was dating Penny from the cartoon "Inspector Gadget". This inspired our GM to run a session in which Dr. Zin teams up with Dr. Claw and inspired a friend of mine to grumble, "If Popeye the Sailor shows up, I'm walking!"
"All the World's a Stage and Everyone's a Critic" — Mervyn Alquist