48. Mephisto

Besides moonlighting as a Marvel villain, Mephisto is also the ruler of Hell and the comic book version of Satan. Spooky. He can shape shift, change time and has superhuman strength. You can try to kill him, but he will regenerate, so don't waste your time. His strongest ability though is his power of manipulation.

He is also buddies with Death. The two made a pact where Mephisto would be allowed to keep the souls of the dead. He can also keep the souls of the living but only with their permission. He is not buddies though with Silver Surfer or Thor, seeing as they're sort of opposing examples of what mankind could become if positivity and good cheer got its way.

He pissed off Doctor Doom by holding the soul of his mother, Cynthia von Doom, captive. He took the soul and brains of Mister Fantastic, his wife Invisible Woman and even their son Franklin Richards when they screwed up an exorcism.

That's not even the good stuff. When the Scarlet Witch tried to use magic to have babies with her husband Vision, she accidentally summons two shards of Mephisto's soul, which then became her infant twins. When she finds their true origin, Mephisto sucks them back into his body. Scarlet Witch then goes nuts because of it. Clearly, Mephisto is not one with whom to mess with.