Wasp (real name Janet Van Dyne) is a superheroine with the ability to shrink and fly. At one point she was a member of the Avengers, when Iron Manreassembled the team he did not recruit Wasp.
Janet Van Dyne was a woman who gained powers through a procedure involving Pym Particles. She was the girlfriend and later wife of scientist Hank Pym, who was the original Ant-Man. Van Dyne became a superhero known as Wasp, and alongside Ant-Man, fought crime and supervillains. Eventually, Wasp and Ant-Man joined the Avengers, and fought alongside them until they had disbanded. She hasn't yet rejoined.