Apparently if Professor Xavier hadn't stopped Apocalypse, then Apocalypse would have taken over the world. That was the whole plot of the series. Wolverine and Cyclops got into a battle that cost Cyclops an eye and Wolverine a hand. X-Man was born from Cyclops and Jean Grey's DNA. The Dark Beast was born, without Prof X's guidence. Etc.

Doctor Doom is another classic Marvel Super Villian. He seeks to make the world better by ruling it. He figures that being Emperor of the planet would bring about world peace and an end to hunger. That those in power stand in his way. He also seeks to free the soul of his dead mother from that bad place that Mephisto rules over. But mostly it is the rule the world plan that he follows. He makes robots called Doombots that look like him, and sometimes they get defeated. Ben Grim was often quoted as saying "I wonder if Doctor Doom was a real guy or a robot?" many times. Also his hatred for Reed Richards leads him to clash with the Fantastic Four a lot. Sometime happened between them in college and Doom blamed him for the accident that scared his face. In a "What If" comic book, they had Doom as a hero, who actually listened to Reed and double-checked his formula and it didn't blow up in his face and he wore gold armor and battled for good. So it is possible that Doom could be a hero. They also did this in the Doom 2099 comic book, that had Doom go up against villians.