It's no secret Keiji Inafune and his diminutive team of artists looked to their youth when creating the earliest Mega Man characters. In development of the first Mega Man and Mega Man 2, character designs were heavily inspired by Japanese animation and Tokusatsu entertainment of the 60's and 70's, some more than others. Case in point: Quick Man.
Though fans are quick to point at Casshan as the sole source of Quick Man's inspiration, our boomerang-headed-friend bears more than a passing resemblance to a character from 1976's Pro Wrestling Star Azteckaiser. The show chronicles the adventures of a pro wrestle who thwarts the demonic Black Mist Wrestling Federation on a weekly basis. In the 21st episode, the titular Azteckaiser goes up against Grocaru Hill, a cunning cyborg.
Grocaru Hill's facial features and broad shoulders look familiar, no? While the cyborg isn't as fast as Quick Man, his trademark weapon, much like his Mega Man counter part, is a boomerang. A boomerang. That certainly provides more credence to the fact that Quick Man was originally conceived as "Boomerang Man," according to Mega Man: Official Complete Works.
While Casshan certainly had a hand in Quick Man's design, I think it's safe to say the lesser-known Glass Hill laid a fair bit of groundwork, too. It makes you wonder if any more Robot Masters yield from obscure sources, too.
Credits: takeda1976, TETSU100%, this fellow's blog