A shapeshifter, and a mutant. She can look like you whenever she wanted. Unsure if she can become like a bird as a raven. Her name is Raven, but more known as the Mystique. If you relied on the movie versions, not giving attention to the comics and animated series, you may consider her as villain initially. She's allied with Magneto, but eventually betrayed and died.
Prequel of the film series came. Mystique became a bigger character. With four movies of the series, but she accidentally died at the last one. It triggered the fight between the mutants, but it was a sad moment to lose an important character, who has such a motherly traits towards younger mutants.
Uncertain about the future of the film series. Will it become part of the cinematic universe? Or will it be a standalone series? For sure new actors will be portraying, but Jen portrayed well as Raven/Mystique. By the way, there's a character with the name Raven from the Marvel's rival.