The Thunderbolts are one of the most dangerous teams on the Marvel roster. While it is normally comprised of super villains and criminals, a few vigilantes and anti-heroes have also been a part of the group. It's formed many purposed over the years.
It's been used for villains to masquerade as heroes, to try to reform criminals and even as a way to control these masterminds into doing something good rather than constantly causing destruction. However, there are some villains that seem like they would fit in well to the Thunderbolts that have never been featured as part of the team.
10 Doctor Doom
Doctor Doom is an absolute mastermind when it comes to plotting villainous plans. It's a surprise therefore that none of his evil plots have included the Thunderbolts as collateral damage.
They've proven in the past to be an easy team to manipulate because there are so many grey areas about how they morally operate. Perhaps it's a team he won't overlook for much longer.
9 Prowler
Prowler, the uncles of Miles Morales, has been known to work alone on many occasions. He doesn't often fit into teams but is rather a hired hand for those paying the right amount.
He would make a really interesting addition to the Thunderbolts though, as he is a character that has twisted and turned in various versions about where his heart truly lies.
8 Mystique
Mystique is yet another villain who's jumped between villainy and heroism before. She has been manipulated in the past by the likes of Magneto and the Brotherhood of Mutants.
She'd be an interesting fit for the team as she'd likely try to create havoc, masquerading as various members of the group and causing drama. She'd also be incredibly useful in the field for a variety of their missions though.
7 Absorbing Man
The Absorbing Man does exactly what his name suggests, being able to absorb any material and turn his body into it. He is quite obsessed with boosting his powers which the Thunderbolts could take advantage of.
He'd be an easy villain to control as the agency controlling the team could threaten him with terrible materials and reward him with something he'd never normally be able to get his hands on.
6 Lorelei
Lorelei is the sister of the Enchantress and usually overlooked in terms of her own super-villainy. She can control many men with the power of love which is a useful gift to have.
Throwing her into the chaos that is the Thunderbolts would be a recipe for disaster but also great in terms of the reader's entertainment. It's surprising no writer has wanted to utilize her in this environment.
5 Purple Man
The Purple Man has harassed and tortured Jessica Jones for years, proving himself to be one of the most despicable villains. He's worked within other criminal groups before, including the Hood's Gang.
However, he is yet to appear in the Thunderbolts, which is strange because he'd be such a valuable asset. The most likely reason why is because he'd be very difficult to control.
4 Nightshade
Nightshade has been a long time Luke Cage villain and an extremely dangerous, intelligent, member of the criminal underworld in Marvel Comics. She has even been able to create a serum to turn men into werewolves in the past.
Despite her genius and undeniable abilities in the field, she has yet to be a part of the Thunderbolts team. She's a character that isn't used often and would be a really fresh choice for the group.
3 Whiplash
Whiplash is an incredibly famous Iron Man villain, although there's been multiple versions of the character. While one spin-off has been part of the team, the famous Anton Vanko has not.
Using a specialized mechanical suit, with electrical whips, it would be easy to build in a way to control the character into this armor. He's an often overlooked villain with great potential that could become an unexpected leader of the team if given the opportunity.
2 Viper
Viper, who is sometimes known as Madame Hyrda is a character that has been on the brink of success for most of her criminal life. She's helped the evil organization reach new heights under her leadership.
Despite the success she has had with Hyrda, she's never really turned her hand to other groups; especially not the Thunderbolts. While her colleague Baron Zemo has used the group, Viper is yet to do so.
1 Tiger Shark
Tiger Shark is the perfect kind of villain to have on the Thunderbolts. He's terrifying, offers up a unique skill set, but is just primitive enough that he can be controlled.
He could essentially become like King Shark in the Suicide Squad, but Marvel's own spin on this. It's surprising therefore that's he never been used as the grunt of the group. Perhaps there are some career opportunities in the future for him.