I'm gonna use this thread as an excuse to rant about a character I've always felt was underutilized. How underutilized? So underutilized that I think the only games he's in are an MMO and a Lego game. But his franchise has lots of video games, and the /co/ sucks, so I'm gonna talk about him here.
The Ultra-Humanite is the first supervillain ever. First appearing in Action Comics #13, one year after Superman's first appearance. For the uninitiated, Superman is widely considered the first superhero. Yes, there were pulp characters that definitely influenced his creation, and if you want to argue about it, you could make a case that Gilgamesh, literally the oldest character we know of, is a superhero. But Superman is the first modern superhero, and The Ultra-Humanite is the first supervillain he ever fought. In his first appearance, Superman is investigating corruption within the taxicab union and finds out that actually it's the work of a crippled old scientist who calls himself The Ultra-Humanite. Ultra, as Superman would come to call him, also says that Superman has been foiling many of his schemes over the past year, implying that many, or even all of, the adventures that Superman had up that point were actually the work of Ultra. Anyway, the clear point here is that Superman's most threatening villain, who might have been behind all of his threats in his career thus far, is a crippled genius. It's an obvious brains v brawn thing, and it works great.
After like two adventures, including one where he failed to swap bodies with Superman, he put his brain in the body of famous actress, Delores Winters. This got him out of his old crippled body, and also meant that the police and Superman would go easy on him, or her, because he's a girl now, and everyone refers to her as female, because she has a pussy, and nobody considered this a confusing issue in 1939. She tries to seduce Superman and make him her lackey, but he realizes she's Ultra, so that doesn't work out. Anyway, Ultra's schemes get a lot more complicated than making the taxicab union go on strike, and involve things like weather control. In fact, I think she might be the first character ever to have a secret volcano lair. But after a couple of defeats in her female body, Ultra throws herself into the open crater of her secret volcano lair, joining the 50+% of her kind.
Very shortly after, Superman would meet a new mad scientist supervillain, Luthor. Luthor has his own extremely convoluted continuity. For a very light example of this, he started as a redhead, but due to a ghost artist getting Luthor confused with one of his own minions from a previous issue, at one point he got drawn as a bald guy, and that stuck. That also made him look more like Ultra-Humanite's original body (though not quite the same, since he wasn't an old guy in a wheelchair). But the important part is that he would quickly become Superman's arch-nemesis, and Ultra was completely forgotten. There was a new bald mad scientist in town.
Over 40 years later, Ultra would re-appear, revealing that she survived and put her brain in the body of an albino gorilla. That gorilla was male, btw, so he's a he again now. However, in the intervening years, the Superman series had actually switched to focusing on a completely different Superman from a completely different universe. In the '60s they retconned it so most of the earliest comics from the '30s through the '50s took place on an alternate world called Earth-Two. This was used to explain differences between early continuity and later continuity. For example, redhead Luthor was from Earth-Two, while bald Luthor was from Earth-One, the main universe. For characters that had been published continuously, it was treated as if stories very similar to Earth-Two stories also happened on Earth-One, but any elements contradicted by later stories didn't happen, and only happened on Earth-Two. I don't know if anything says that no version of The Ultra-Humanite existed on Earth-One, but as far as I know, no such character was ever referenced. The Ultra who threw herself in a volcano and came out as an albino gorilla was on Earth-Two, AKA not the main universe, and the Superman he fought was no longer the main Superman. But he was back and he fought the now older Superman of his universe, as well as the rest of the Justice Society, the equivalent of the Justice League in that universe. Also they did a series called All-Star Squadron which was set in the '40s, and that series revealed how Ultra survived the volcano, and she did a bunch of other schemes before getting the gorilla body. This set Ultra very firmly in the WWII era for many stories important to his history.
In 1986 DC realized that whole Earth-Two thing was complicated, so they merged all the universes (well, actually like six others survived, but they don't count). So now The Ultra-Humanite always lived in the main universe in the new history. However, they didn't want Superman to be an old man who was around back in WWII, like the Justice Society guys. They wanted him to be the age of the Justice League guys, who were all basically in their early '30s. They said Superman first appeared "ten years ago," and Batman and the rest of the Justice League guys followed shortly after. The Justice Society guys were old because them fighting in WWII was important, so even though originally they appeared after Superman, now they appeared decades before him. Now Green Lantern (Alan Scott) was the first superhero in modern history, and Superman was the first of the second generation.
But wait! Superman, Batman, Wonder Woman, Green Arrow, and Aquaman were around in WWII, but were also members of the Justice League. In the old continuity, they explained this by saying there were two of them, one in each universe. But now there was only one universe. So what they did was they made up new characters who were similar to those five, and said that in the new history, those new characters existed in WWII, rather than the old ones. So Superman wasn't around in the '40s anymore, but all the stories still basically happened, only now instead of Superman they were done by a character named Iron Munro, the illegitimate son of Hugo Danner, the protagonist of Philip Wylie's novel, Gladiator, which Superman essentially plagiarized. By the late '80s, Gladiator had fallen into the public domain, so DC Comics felt comfortable admitting this. Batman's role in the Justice Society and All-Star Squadron was largely replaced by Doctor Mid-Nite. Wonder Woman was replaced by explaining that her mother was a previous Wonder Woman during WWII, and Diana Prince just took on her mother's mantle decades later. Green Arrow? Uh... I don't know if they ever explained him. Aquaman they straight up forgot until like 2019 when they finally remembered that there should have been a WWII Aquaman, and did a story about how everyone's memories of him was erased.
So now Ultra-Humanite existed and was still occasionally fighting the Justice Society and others, but he never had his history with Superman, and was never really acknowledged as the first supervillain, which is pretty damn lame. Meanwhile, Superman ended up fighting a few new villains that were called The Ultra-Humanite, but they all sucked and nobody cared. Some of them weren't even similar in concept, and were just random monsters or whatever. Ultra did have a notable role in the 2000s Justice League cartoon, but that's of course a different continuity. Also, all he was there was an albino gorilla with a giant brain. It's just not the same without his history of being the first supervillain, and a very obvious brains v brawn setup. But now he's most known for being a big-brained albino gorilla.
Meanwhile, Delores Winters survived her body swap, but was driven mad by the experience. Decades later she swapped bodies with her daughter, essentially so she could be young in modern stories, and look like her old self (who actually we only saw as Ultra before). After that she swapped bodies with some ice-themed superheroine that even I forget, so she got ice powers and they started calling her Endless Winter. I'm pretty sure she got killed shortly after that.
Notably, Earth-One Superman didn't start his superhero career in Action Comics #1. They retconned it back in 1945 so that he was a superhero called Superboy when he was a kid. This made it so Ultra wasn't the first supervillain he ever fought anymore. Indeed, he fought Luthor, both kid and time travelling adult versions, on many occasions. However, when they merged the universes in 1986, Superman's history was changed so he was never Superboy now, but this was the same time they said he wasn't operating in WWII, and made it so he never fought Ultra. Indeed, Superman got several retellings of his origins and early days since, but Ultra was never brought back into his early history. Instead he just always fights Luthor, villains created by Luthor (like Bizarro and Metallo) and Brainiac. Presumably Ultra's stuck with his origin in the WWII era and still fought those guys, but it's just not the same if he doesn't fight Superman, too.
Also, in the '50s, Superman first met Brainiac, who would go on to become his second arch-nemesis. More powerful than Luthor, but not quite as personal. Still, those two are the big ones, and Brainiac notably also has a penchant for body swapping. He didn't originally, but in the '80s they wanted to give him a new toyetic body, so they had him put his brain in a robot body. Well actually, he was revealed to be a robot very early on, but a robot designed to look like an alien so he could spy on alien civilizations and they wouldn't realize he was a robot. But by the '80s he gave up on that and just had a cool mecha body. In the late '80s after history changed, they rebooted him and now they said that actually Vril Dox, the real guy who the original Brainiac spy body (and mind) was based on, who was being executed for treason by the Computer Tyrants of his home planet, Colu, happened to be contacted by psychic Milton Fine, on Earth, right before his death. Milton Fine was a circus sideshow who used the stage name "Brainiac" and basically just pretended to be a psychic, but actually it turned out he did have powers. But Vril Dox had a much more powerful mind, due to his extreme 12 level intellect. (Luthor, by far the smartest human, has a 10th level intellect.) So basically Dox possessed Fine. But to keep his control, he needed to eat brains. Yeah, I don't think this has much to do with old Brainiac either. Old Brainiac was a guy who liked to go around and shrink cities with a ray gun, so he could collect them in bottles. But notably, this story was so different that it didn't fully mean that old Brainiac could never have existed. But he wasn't referenced again, at least for a very long time.
Anyway, Fine Brainiac ends up swapping bodies a few more times (I think he takes the Milton Fine parts of his mind with him, but Vril Dox has long since been in full control), including notably once putting his brain in Doomsday's body. After he killed Superman, Doomsday lost subsequent rematches, partially due to basically being a mindless beast. But with Brainiac's mind, he should be able to win. But of course he didn't. Later they revealed that actually the original Brainiac was around this whole time, meaning basically a second copy of Vril Dox's mind, and the copy that went into Milton Fine's brain was just a "probe" (so presumably communicating with the original Brainiac) and thus basically became irrelevant. Later they established that there were apparently way more Brainiac probes. So basically, Brainiac completely stole Ultra-Humanite's body-hopping gimmick.