The Punisher doesn't beat around the bush. He hates crime, so he kills criminals. But every now and again, writers spice Frank Castle up with some screwball alternate realities. Read about the Punisher going to the post-apocalypse, heaven, and Riverdale.
Marvel recently announced that the Punisher would be going the I Am Legend route, with Marvel Universe Versus the Punisher, a miniseries set in a post-apocalyptic America in which the Punisher is the only human left alive. According to series writer Jonathan Maberry:
The short version is that a pathogen is accidentally released that was designed during the Cold War to allow humans to adapt to climate changes resulting from a nuclear or biological war. The pathogen changes human physiology so that it can survive in any environment; and it amps up the aggression/survival instincts. Unfortunately, it was never fully tested and it has dreadful, unforeseen side effects. The Punisher is there at the time of the pathogen's release and gets a "super dose" of it, which renders him immune to the effects that transform virtually everyone else on earth.
This isn't the first time Frank Castle has gone up against the entire Marvel Universe (he's done it twice before, in fact). Here are some of Frank's stranger forays in parallel universes.
1.) Punisher: The End (2004)
In this Garth Ennis-penned one-shot, global nuclear war destroys the entire planet, bathing the Earth's biosphere in toxic radiation. The Punisher - who has been incarcerated in the famed Sing Sing Correctional Facility - survives by taking refuge in the prison's fallout shelter. Eventually Frank and a fellow prisoner must go to a mysterious bunker under the remains of the World Trade Center. This is perhaps one of the bleakest comics ever. Without spoiling too much, this comic illustrates how monomaniacal Frank's quest for justice is - punishment trumps extinction.
2.) Punisher Kills The Marvel Universe (1995)
Another Garth Ennis Punisher alt-universe tale! Incidentally, this comic was the first time Ennis ever tackled the vigilante. In this one-shot, Frank Castle is an NYPD SWAT officer and his family is killed in the crossfire between the Brood, the Avengers, and the X-Men. It's a classic, early example of Ennis' vitriol for capes. Here's Frank's reaction to his family's death...
...and later he becomes an agent for a shadowy cabal of people mutilated by superhuman tiffs. This battle with Victor von Doom is priceless. In another great scene he drops a nuke on the X-Men...on the moon.
3.) Archie Meets the Punisher (1994)
In this classic crossover, Punisher tracks "Red," a drug dealer and (Archie lookalike!), to Riverdale. The Punisher poses as a Riverdale High gym teacher and tracks the perpetrator to one of the thousands of sock-hops Archie and his immortal friends are condemned to attend until the sun snuffs out.
No, Frank! Don't throw a cake! Otherwise Ms. Grundy will give you detention and you won't be able to go to Pop Tate's Chock'lit Shoppe!
4.) Punisher: Purgatory (1998)
In this lamentable miniseries, the Punisher commits suicide (?!?) and is resurrected by the heavenly host as a demon hunter decked out with two boss angelic sidearms and a sweet sigil tattooed to his forehead. Although this story occurred in mainstream Marvel canon, Garth Ennis retconned it shortly and sweetly when he began his Marvel Knights Punisher run. Says Frank Castle in 2000's Punisher 1:
I caught a glimpse of heaven once. The angels showed me, The idea was I'd kill for them. Clean up their mistakes on earth. Eventually redeem myself. Tried it. Didn't like it. Told them where to stick it.
To the best of my knowledge, no one's referenced it since. Imagine if Spider-Man suddenly gave up his mantle and became "Peter Parker, The Crime-Fighting Racecar Driver," and you'll get a good sense of fan reaction.
5.) Punisher: A Man Named Frank (1994)
It's not hard to imagine Frank as a high-plains drifter in 1898 New Mexico, but van Damme. Look at that cover. This is perhaps the least dignified we've ever seen him, and that's saying a lot. Jon Voight circa 1969 ain't your look, Frank.