Mystique (Wolverine and the X-Men)

Mystique is character from the animated series ''Wolverine and the X-Men. ''She a mutant shape-shifter and one of Magneto's henchmen. True to her name, nothing is known about her. She is a former lover of Wolverine.

Personality
Mystique is hard, cold, and of course, mysterious. She does whatever it takes to get what she wants. Despite all that, she has shown that deep down she is able to care about others, namely Wolverine.

History
She was once part of Weapon X until Wolverine freed her and told her to run away as he held off Sabretooth as long as he could.

After escaping, she somehow joined Magneto's cause to make humanity fear mutants, doing saboteur and espionage missions on the M.R.D. and the X-Men.

She seems to be helping Wolverine to save Maverick and his daughter from Weapon X, having a goodness in her heart as her returning the favor to Wolverine for saving her. She later told Wolverine that before had his memory wiped that they were lovers but that he is no longer the man she loved. She later left and rejoined Magneto.

She was later ordered by Magneto to impersonate Senator Kelly and to reactivate the Sentinel Program and have them deployed to Genosha.

Trivia

 * It's rumored that Mystique's maternal connection to Nightcrawler would have been revealed in season 2 had it not been cancelled.