This is a collection of different fictional worlds that have crossed over with another world. In that I mean a specific story where characters from one world actually met characters from another. This excludes some fighting games like Marvel vs Capcom, because to the best of my knowledge those games didn't actually have a story. It also excludes incidents where a product from one world appeared in another, such as the Daily Planet newspaper appeared in a John Sable comic. Public domain characters are not included, with a few exceptions, as they are free for anyone to use. Lastly this not saying that the characters in the worlds listed below are all in one Universe, as the Wold Newton Universe hypothesizes. It is just illustrating connections between various worlds. Think of it as 6 degrees to the Marvel Universe.
Included in the Marvel Megaverse
Ultraverse (Crossed with Conan, and the Nightman TV show crossed with Manimal)
Razorline
New Universe
Shadowline
Supreme Power
Possibly the world of 1984
Ultimate Universe
Marvel Zombies (Crossed with Evil Dead, See Evil Dead Below)
Transformers (Connecting it to the Transformers Multiverse, which include the various cartoons, movie, and alternate universe comics like revolutions, and various G.I. Joe crossovers.) Battle Beasts was originally a Transformers spin off. GO-Bots are also linked to them. Consequently the Go-Bots spin off Rock Lords would be as well. Also the Transformers toy line was derived from a Japanese toy line called Microman, which in turn was a spin off of Japanese imports of G. I. Joe
G.I. Joe, which the Transformers crossed with, also linked to Jem and Inhumanoids. The world of M.A.S.K. is also now merged with G.I. Joe
Marvel Crossed over with
Star Trek
A Star Trek novel references TV shows the Pretender, and Beauty and the Beast
Image
Archie
Shi
Evil Dead
Valiant
Which crossed with Image
And Nexus,
Which crossed with Badger and several other First series (American Flagg!, GrimJack, Jon Sable: Freelance, Whisper and Dreadstar) during the First Comics miniseries Crossroads
DC universe and Marvel merged into Amalgam universe, which still exists. Access lives between both universes. Some time in one, some time in another. Can tell when someone has crossed over. Crossovers happen briefly (Marvel DC published crossovers afterwards) but Access makes it so no one remembers.
Also during the JLA/Avengers crossover one Earth was created where DC and Marvel characters existed side by side. Numerous Marvel DC crossovers may have taken place on this earth. Amaglam also has an Earth One version, where all the characters were in WWII.
The DC universe crossed over with:
Aliens and Predator
Danger Girl
He-man.
Grendel
Hellboy
Judge Dredd
Madman
Mortal Kombat
Tarzan
Thundercats (Which crossed with Battle of the Planets)
Terminator
Vampirella
The Batman TV show crossed with the Green Hornet.
Image comics originally had 6 Studios of different characters that made up one shared universe. Those six studios are,
Extreme Studios, owned by Rob Liefeld.
Characters in this studio are
Supreme Youngblood Glory
Highbrow Entertainment, owned by Erik Larsen
Savage Dragon, Vanguard, Freakforce, Superpatriot
Shadowline. owned by Jim Valentino
Shadowhawk
Todd McFarlane Productions, by Todd McFarlane
Spawn
Top Cow by Marc Silvestri
Cyberforce, Witchblade, Darkness
Eventually an event called Shattered Image separated these universes, (acknowledging that Extreme Studios already split with Image before the story was printed.) Top Cow eventually struck out on there own, and Wildstorm was bought by DC comics. The six original studios and some of their main characters are listed)
Highbrow Entertainment crossed with
Mars Attacks
TMNT, Who met Usagi Yojimbo,
who met Cerebrus, both met Flaming Carrot
TMNT also met Power Rangers,which were
based on Dinosaur Squardron
Battle Pope,
Megaton Man,
Marshall Law, Who met Hellraiser
Destroyer Duck
There was a Savage Dragon Cartoon that had a thematic crossover with with Street Fighter, Mortal Kombat, and Wing Commander Academy cartoons.
Top Cow crossed with
Tomb Raider,
Joe Quesadas ASH,
Painkiller Jane
and Vampirella, who met Painkiller Jane, and Shi
Shi met Razor? Fallen Angel, Tenth Muse,
which met Telios,
Frankenstein Mobster,
Also met Chaos comics characters Purgatory, Lady Death, and Evil Ernie,
who met Hack Slash, who in turn met Chucky from the Child's Play movies
Wildstorm crossed with Aliens. Aliens fought Predator.
Predator has crossed with
Comics Greatest World (Dark Horse),
Which crossed with the Shadow, who met Doc Savage
Predator also met Judge Dredd
Tarzan. who met Jon Carter
Terminator, who met Robocop.
Tomb Raider
Image as a whole crossed with Valiant
This is a separate list of video game crossovers.
Street Fighter, in the Capcom vs SNK, and vs Namco games, also crossed with other Capcom titles. The storyline for Capcom vs SNK: Millenium Fight 2000, according wikipedia, is
"In AD 2000.
A special martial arts event is planned through a collaboration of the two most powerful world organizations: Garcia Financial Clique and Masters Foundation. The gala event – it is hoped! – will ease the political conflicts between the two powers.
Its name was "Millennium Fight 2000.
Many renowned martial artists have registered for the tournament. People around the world focus intensely on the upcoming exhibitions.
The long-awaited opening ceremony is a huge success.
No one notices the signs of impending chaos..."
The Capcom games are listed below.
Captain Commando
DarkStalkers
Dino Crisis
Final Fight
Forgotten Worlds
Ghosts N Goblins
Megaman
Red Earth
Resident Evil
Rival Schools
Strider
SNK Games:
Art of Fighting/Fatal Fury/Savage Reign/Kizuna Encounter
Athena
Buriki One
Ikari Warriors
King of Fighters (Includes many franchises on this list)
The Last Blade
Metal Slug
Psycho Soldier
Samauri Showdown
Soul Caliber
World Heroes
Capcom vs Namico, according to wikipedia, went like this.
"The game centers around two original characters created for the game named Arisu Reiji and Xiaomu. The two of them work for a special unit called Shinra and they are tasked with investigating spirit and otherworldly disturbances. They are initially investigating a strange "sleeping sickness" in the Shibuya area of Japan, when it becomes apparent that something much larger is at stake. Characters, both good and evil, from other times and other worlds begin appearing in Japan in the year 20XX."
The Namco games that appeared are as follows.
Baraduke
Bravoman
Burning Force
Dig Dug
Genpei Toma Den
Kloana
Soul Caliber
Tales of Destiny
Tekken
Tower of Druaga
Valkyrie no Denestu
Wonder Momo
Xenosaga
Shadow land
Capcom characters in this series are the same with the addition of Rockman Dash.