A serial killer who goes by “The Mask.”
His greatest strength is his powers of observation. He stalks someone for a year, then on New Year’s Eve he murders them and hides the body. He then impersonates his victim for the next year (or until he gets bored living their life) all the while stalking his next kill. When he moves on, his last victim’s family and friends find out about the murder- a year after it happened. As a younger man he made a lot of mistakes, so he thinks that doing this gives him second chances at life.
[credit:] swordtech @ NaNoWriMo