4. Barbara Morse (Mockingbird)
Barbara "Bobbi" Morse is Mockingbird, a level 6 trained S.H.I.E.L.D agent who graduated at the top of her class. While she has no superpowers as such, Mockingbird is proficient in several forms of hand-to-hand combat and is familiar with a wide range of weapons. She usually uses a pair of batons which can be combined to form a single bo-staff in combat and these are weapons with which she has great expertise. When she sustained a mortal injury out in the field, she was injected with an experimental serum combining the Super Soldier Serum that gave Captain America his strength and the Infinity Formula that has retarded Nick Fury's ageing in the comics. As a result of this her injury healed and she has since exhibited greatly enhanced physical strength and agility. She's also a blonde bombshell and you can never have too many of those!