8. Hercules
Hercules could be used in so many different ways in the MCU that it's a crime he hasn't really been mentioned as a potential addition. Marvel has delved in to Norse mythology with the big screen adaptation of Thor, which features legendary figures such as Thor himself, Odin, Loki and Frigga, so it's not beyond the realms of possibility that they might want to produce a big screen adaptation of their characters from Greek and Olympian mythology, such as Zeus, Ares, Apollo and Hercules (who is Greek, not Roman, in the Marvel comics, as he is based on Heracles). Hercules is a real powerhouse who is a highly skilled hand-to-hand warrior and who possesses powers such as superhuman strength, speed, stamina, reflexes, endurance and durability, essentially immortality, a healing factor, an immunity to all Earthly diseases and a limited resistance to magic. As the son of a Skyfather, but from a different pantheon, Hercules has been shown as a big rival of Thor. However, he has also been an associate of the Thunder God - and indeed other heroes - as part of the Avengers (as well as numerous other heroic super-teams). He could be brought in to the MCU in his own movie, as a Thor rival or as part of the Avengers - and all of those scenarios would be awesome.