10. Justine Hammer (Crimson Cowl)
Justine Hammer is the daughter of an existing Marvel Cinematic Universe character, Justin Hammer - Tony Stark's business rival who recruits Ivan Vanko to build him armoured suits, but is betrayed by Vanko and sent to prison by Pepper Potts. Justine's life was not a privileged one, despite her super-rich Father. Her Father never approved of her and she was always trying to prove her worthiness. She eventually decided to follow in her father's footsteps and use the supervillain community to accumulate power for herself. As a capable fighter herself, she donned a red outfit (containing technology that allowed her to fly and teleport, amongst other things), called herself the Crimson Cowl (an alias once used by upcoming MCU villain Ultron), put together an incarnation of the Masters of Evil and began working on a street level for HYDRA, looking to impress New York mob bosses. Operating at that kind of level would make her an ideal villain for the Agents of S.H.I.E.L.D show and with entities such as Justin Hammer and HYDRA already existing in the MCU it wouldn't be too difficult to introduce and integrate her.