10 Most Evil X-Men Villains
4. Mister Sinister
A Victorian geneticist named Nathaniel Essex, Sinister's experiments on himself have kept him alive for centuries and given him telepathic and shape-shifting abilities (aka he can do whatever the plot needs him to do powers). He is known for allying with other big name villains, but he is also a considerable threat all on his own.
Sinister is obsessed with the X-Man Cyclops and has been manipulating his entire life since birth. He cloned Jean Grey to create Madelyne Pryor, a woman who Scott married after Jean sort of died a bit, as part of a plan to continue his twisted experiments on their son.
His most well... sinister act though was initiating the Mutant Massacre. Essex sent his gang of cloned mutant thugs known as the Marauders to the home of the Morlocks, a community of mutants who lived underground, and had them start killing everyone there. The X-Men were able to prevent the Morlocks from being completely wiped out, but the bodycount was still in the hundreds and a lot of the X-Men were badly injured.
So why did Mister Sinister do all of that? He saw that another scientist had used his work to genetically tamper with the Morlocks and he didn't like his work being copied.