2. Abomination (The Incredible Hulk)
Emil Blonsky was a special-ops operative of the British Army until he joined the Hulkbuster team under General Thunderbolt Ross. Even as a human he was somewhat unpredictable and temperamental. He was initially injected with a small dose of the previously abandoned Super Soldier Serum and later gets injected with Bruce Banner's gamma-exposed blood, causing him to transform into the Hulk-sized Abomination. The combination of the two substances granted him massively increased durability, incredible healing powers (enabling Blonsky to heal within a couple of days from having every bone in his body broken, even prior to the transformation in to the more powerful Abomination), vastly increased speed enabling him to outrun any human with extreme ease, vastly increased reactions, given that he could catch a shell fired from an RPG, he could leap several stories high from ground level and of course he possessed strength to rival the Hulk and as such he could use heavy chains and vehicles as weapons. The fact that he became completely and utterly unstable in the head, post-transformation, makes him even more dangerous. He wouldn't think twice about turning you in to paste even if you didn't get on the wrong side of him - so heaven forbid if you did.