The Joker is one of DC Comics' most evil rogues. The Clown Prince of Crime is a murdering sadist who has killed hundreds of people over the course of his career. While the Joker was once a more lighthearted antagonist to the Batman, the modern interpretation of the Joker is often that of a nihilistic spree killer who would wipe out the world as a gag.
That said, the DC Multiverse is a big place with many alternate worlds in which the Joker could be a less vile human being. There are even some worlds where the Joker can be the sanest one in the room, as these iterations show.
5 Three Jokers Fight Against Superman In Tangent Comics
Tangent Comics was a DC imprint that existed for a year starting in 1997. It portrayed alternate versions of the DC Universe where established characters were reimagined and put in a new context. On Earth-9, the Joker is an identity used by three young women: Mary Marvel, Christy Xanadu, and Lori Lemaris. The intention was to have one superhero "do the job of three." This version of the Joker was created by Dan Jurgens, Karl Kesel, and Matt Haley.
This Joker fought on a superhero group called the Secret Six and did a lot of good with the team. Unfortunately for them, a telepathic, telekinetic counterpart to Harvey Dent became this world's Superman (created by Mark Millar and Jackson Guice). Tangent was revived in 2008 with Superman's Reign by Dan Jurgens and Matthew Clark. In this story, the Earth-9 Superman conquers his world and captures Mary Marvel. He forces her to reveal the names of the other two women who used the Joker identity before dying. Thankfully, Lori and Christy were still alive when this world was last visited in a comic.
4 Joker Became A Rallying Symbol Against The Regime In Injustice
In Injustice: Gods Among Us, the Joker uses a Kryptonite variant of Scarecrow's Fear Toxin to make Superman believe that his pregnant wife, Lois Lane, was the monstrous Doomsday. Superman quickly killed Lois and then realized what he had done. In retaliation, Superman punched a hole in Joker's chest.
Superman subsequently conquered the world and established the Regime. Despite the Joker's final act being something so monstrous, the Joker became an icon of the anti-Regime resistance movement. A group called the Joker Clan formed, led by Harley Quinn. Unfortunately, the Joker of Earth-1 arrived and stole the Joker Clan out from under her. Harley then founded the Harley Horde, and the two groups clashed. That said, they still made it their mandate to fight the Regime whenever they could.
3 He Fights Against The Crime Syndicate On Earth-3
There are a few variants of the Joker on different versions of Earth-3. Generally, Earth-3 is the home to the Crime Syndicate, a dark reflection of the Justice League that rules their Earth with an iron fist. Originally, Alexander Luthor was the only hero of that world who stood against the Crime Syndicate, but more recent versions of Earth-3 have had other villains as heroes fighting the Syndicate.
One version, called the Jokester, was created by Paul Dini, Manuel Garcia, and Keith Giffen. He fought against the Crime Society, before was ultimately killed by a renegade Monitor. A more recent Joker on Earth-3 was designed by Geoff Johns and Ivan Reis, he fought a chaotic war against the Crime Syndicate. He felt the collateral damage that ensued was worth it, but he didn't feel good about it. He was recently rewritten with the finale of Dark Nights: Death Metal by Scott Snyder and Greg Capullo. The new version of this Joker is a hero called the Jester, but he was killed by the Crime Syndicate as of Crime Syndicate #5 by Andy Schmidt and Kieran McKeown.
2 The Joker Lantern In Batman: The Last Knight on Earth
In Batman: Last Knight on Earth by Scott Snyder and Greg Capullo, a clone of Batman (created by Batman's own resurrection machine) emerges into a post-apocalyptic world destroyed by global chaos set off by Lex Luthor. This new world is controlled by someone called Omega, who uses Darkseid's Omega Effect to maintain order in what remains of this Earth.
One of the first things that this new Batman finds is a lantern with the head of the Joker somehow still alive and speaking inside. Batman takes this Joker lantern as a companion, and he keeps the Dark Knight company as he works to find a way to dethrone Omega. This Joker is strangely friendly and compassionate, and he even encourages Batman whenever he can. He is even given a robotic body to become Batman's new Robin.
1 The Joker Is A Principled Anarchist In Batman: White Knight
In Batman: The White Knight by Sean Murphy, the dynamic of Joker and Batman is vastly different. The Joker is an anarchist who focuses on property destruction and makes sure to not take any lives. Batman is a cruel and brutal vigilante who, whether he is aware of it or not, is essentially making property cheaper to be bought up by Wayne Enterprises through his own actions.
After being cured of his insanity, the Joker returns to his old name: Jack Napier. He works to show Gotham the damage being caused by the Batman and the poverty his actions cause and enforce. He rebrands himself as the White Knight and actively tries to get Batman to understand the consequences of his actions.