Adolf Hitler, the intolerant Pauline ruler of Germany, had many brushes with the esoteric during his career. He may have been manipulated by Heinrich Krowler and the Chapel of Dresden. Accounts vary, but at some point rogue geneticist Arnim Zola established a process by which a person could project their mind onto a cloned body. He presented this process to Adolf Hitler. One account showed that in 1944 Zola had already transferred his mind into his current, ESP box headed body. Talking with the Red Skull, he presented him with a pill to use to place himself in suspended animation. Zola presented Hitler with a completed cloned body. After Hitler walked out, Baron Strucker, a fugitive, entered the room. Strucker invited Zola to take part in the establishment of HYDRA. Since around 1944 Strucker would think of Zola in his ESP-box body, this would support that Zola had switched bodies at this point.
However, Hitler as the Hate-Monger would later recall Zola was still in his original body. In any event, Zola prepared a series of bodies for Hitler to use in his new identity of the Hate-Monger. Zola once told Captain America that surgeons had extracted Hitler's brain and that he had preserved it to create a new body for it. This story appears to be a ruse to hide the truth about the Hate-Monger. Since then, the truth behind the Hate-Monger was discovered, and was known to Spider-Man, Silver Sable, and Nick Fury.
Hitler, according to a soldier who was with him the day his original body died, supposedly recommended Zola's process to Baron Zemo ("like your Führer, Zemo, you will become...a God... Zola will see to that"). It appears that Zemo did not for some reason undergo the process.
Apparently in his new cloned body, Hitler established the haven for criminals called Erewhon in South America as well as staging a coup in the South American nation of San Gusto. The latter was foiled by Nick Fury and the Fantastic Four and Hitler was gunned down by his own followers. He later returned in a new cloned body and eventually teamed up with the Red Skull, but the Skull trapped Hitler's consciousness inside an imperfect, non functional version of the Cosmic Cube, thereby eliminating his greatest rival.