3. Apocalypse
Apocalypse is one of the X-Men's most regular, long-standing, intimidating and mighty foes. Born in Jordan 5000 years ago and originally named En Sabah Nur, Apocalypse is a genius mutant who has vast psionic powers and possesses other abilities such as technopathy, superhuman strength, molecular manipulation and energy manipulation. All of these powers and abilities are augmented by advanced Celestial technology, which makes him a truly formidable opponent and villain. His threat is threefold in that he has the physical power to battle the likes of the Hulk, the mental power to battle the likes of Professor X and the intelligence to prepare plans and invent technology to make him a danger to almost anyone. There have been no characters like him in the X-Men movies up to now. His appearance is monstrous and would no doubt require CGI to pull off. However, there's no doubting that he would look incredibly cool on the big screen.