She-Hulk is Jennifer Walters, a lawyer and cousin of Bruce Banner (aka The Hulk). Unlike her famous cousin, Jennifer Walters did NOT acquire her powers via a gamma blast. Instead, she received her powers through a Blood Transfusion from her cousin the Hulk. The radioactive blood caused a mutation and she transformed into the She-Hulk. A female version of the Hulk with similar powers.
Originally created by Stan Lee in 1980. Her character was meant to be a female version of the Incredible Hulk. A little known fact is that She-Hulk was the last character that Stan Lee created until his return to comic writing in 1992 where he created Ravage 2099.
She-Hulk has been a member of several super-hero groups like: the Avengers, the Fantastic Four, Heroes for Hire, The Defenders, and the Fantastic Force. She has also been an Agent of S.H.I.E.L.D. and served as legal counsel to various super-heroes on numerous occasions due to her status as a lawyer.
She-Hulk first appeared in The Savage She-Hulk #1 comic that was released in February 1980.