4. Perrikus
Perrikus is one of the beings know as the Dark Gods - a group of powerful beings who are revealed to be the evil opposites of the Norse gods. In the comic books, Perrikus first appears when he is accidentally freed from a prison in Asgard (having previously tried to invade there many years prior) by the Thunder God Thor. Not knowing what has occurred, Thor departs and Perrikus joins with other entities revealed to be his brethren, the Dark Gods, and they invade Asgard again - this time overrunning it. They succeed in capturing Odin, Thor's father and the ruler of the Norse gods, which emphasises just how powerful they must be. Known as the God of Unlimited Power and Infinite Energy, Perrikus possesses vast superhuman strength and durability (being able to take the combined assaults of Thor with Mjolnir and the Asgardian Destroyer Armour without being effected), as well as the ability to shoot energy blasts and incredibly powerful darts. He has a scythe in his right hand that can cut through, quite literally, anything - indeed he has managed to slice Thor's hammer Mjolnir in half in one instance. Having Perrikus and his allies attacking Asgard would make for one hell of a film and he'd be a massive threat to Odin, Thor and everyone there. Indeed, if he could take over Asgard, he'd be a threat to the entire MCU. He'd also look astonishing with modern special effects.