Serial Number: DWN-017
Designer: Dr. Light & Dr. Wily
Weapon: Needle Cannon
Exactly what Needle Man was designed to do varies by source. According to his backstory, he was designed to break apart boulders and assist with mining operations. However, according to the comics, Needle Man himself states that his sole purpose for existing was to defeat Mega Man. Personally, I'd consider the latter to be the more valid answer, as everyone knows that spike traps instantly defeat the Blue Bomber.
But the most notable thing about this Robot Master is that the design of his NES sprites gives the impression that he has massive buck teeth, which undermines his credibility as a threat.