A comic book supervillain, published by DC Comics. He first appeared in Action Comics #13 in July 1939. In his earliest appearance, Ultra (he's never been given a real name) was merely a scientist and professional criminal, repeatedly vexing Superman and the Justice Society of America, but always escaping to fight another day. He was mortally wounded while trying to kill Supes; his associates, following surgical instructions left by Ultra, preserved his brain and went looking for a new host. They kidnapped beautiful starlet Dolores Winters, killed her, and scooped the Ultra-Humanite's brain into her skull.
The Ultra-Humanite remained in Ms. Winters' body for years, committing crimes galore and even siding with Nazi Germany during World War II, presumably because they let him perform evil experiments on innocent subjects. In DC's pre-Crisis timeline, he eventually traded up for the body of a giant insect, a resurrected tyrannosaur, and a giant psychic mutated albino gorilla with a bulging brainpan. As these monstrous forms never allowed him to attain world conquest, he eventually returned to using human hosts. A few years ago, in the pages of the "JSA" comic book, the Ultra-Humanite took the elderly body of former Justice Society member Johnny Thunder and hoped to use the abilities of the Thunderbolt to rule the world. He was foiled again, of course, but you never know where he's going to show up next...
I always felt that the Ultra-Humanite should have been one of DC's most-feared villains. All the other bad guys killed people and hatched world-conquering schemes, but the Ultra-Humanite stole people's bodies. Sure, the Joker killed people with Joker gas, but the Ultra-Humanite put his brain in your body and used your eyes, hands, and voice to kill others! Sure, Lex Luthor wants everyone in Metropolis to adore him, but the Ultra-Humanite turned Hollywood starlets into posthumous propaganda machines for the Nazis! Can you imagine the repurcussions if some Nazi maniac had killed Ingrid Bergman and used her body to kill concentration camp prisoners and Allied soldiers? If it weren't for that ridiculous name, I don't think there's a superhero or supervillain in the DCU who wouldn't look for somewhere to hide when the Ultra-Humanite showed up...
Informational source: http://www.execpc.com/~icicle/GAULTRAHUM.html
Rant source: It's all Jet-Poop, baby.