She-Hulk is a Marvel Comics character, created as a female counterpart of the Incredible Hulk.  Her real identity is lawyer Jennifer Walters, cousin of Bruce Banner, aka the Hulk.  When Jen was injured, Bruce gave her a blood transfusion, which granted her a reduced version of his own powers.  However, she could control the change at will and would retain her own intellect, unlike Bruce.  Following Ben Grimm losing his powers during the Secret Wars, Jen served as his replacement on the team.  More recently, she has served on both the Avengers and the Future Foundation, become an agent of SHIELD, and served as a lawyer to various super human beings.