3. Mantis
Some female heroes of the era like Moondragon can (mostly) get away with the dreaded plunging v-neck. But Mantis was not so lucky. With her bare-all front, high collar, green-and-yellow color scheme, and Kung Fu moves, Mantis may well have gone to the same tailor as Iron Fist! But that tailor must have sewn together Mantis' costume from remnants the two sides didn't even match! Created by Steve Englehart, Mantis had a lot going for her. She had a unique half-German, half-Vietnamese ethnicity, and she rose from being a prostitute to becoming a member of the Avengers! Though little more than a skilled martial artist, she took on the likes of Thanos and Ultron, insisted on calling herself, "This One," (don't ask) and turned out to be the Celestial Madonna (ditto!). But even that resume couldn't overcome a costume that looked more at home in a southeast Asian brothel than Avengers Mansion.
Mantis made a comeback as a member of the revamped Guardians of the Galaxy, and while she has not been confirmed as a part of Marvel's late-2014 movie of the same name, stranger things have happened! But if she does appear on the silver screen, there's no way it will be while garbed in her unfortunate 1970s costume!