Up in the sky: look! It's an adjective! It's a noun! It's...Adjectivenoun! 

Your friendly neighbourhood superheroes might have thrilling and varied powers and spandex garments, but the way their names are concocted have followed only a handful of formulae in the past 80 years, since Superman sent superheroes soaring. 

(Yes, alliteration is one such naming formula.)

Glen Weldon of Pop Culture Happy Hour traces the supername's development from Adjective+Gender through Colour+Noun to Normal Name and Lone Noun.