5. Sif (Thor)
The gorgeous Jaimie Alexander plays Sif and her battle gear, along with the awesome spear and shield combination that she wields, looks exceptionally cool. With chest and torso armour, arm protection, heavy duty boots, leather-esq trousers, the aforementioned spear and a shield, Sif's outfit screams the word "warrior" and ensures that she is battle-ready at all times. It manages to maintain quite a modern look whilst also possessing elements of real world historic armours (roman, trojan etc) and, for those reasons, it gets a spot on the list of awesome superheroine costumes from live action movies. Alexander is set to reprise her role as Sif in the upcoming Thor: The Dark World.