Norman Pfister was an antagonist in the Buffy two-part episode "What's My Line".
Although taking the form of a harmless salesman Norman was, in reality, a ruthless demonic assassin who used his persona to gain people's trust before brutally murdering them.
He is portrayed by ???
When Buffy became a target for the supernatural order of assassins known as the Order of Taraka it sent a collection of powerful assassins to deal with her, amongst them was the seemingly harmless Norman though it was soon revealed that he was far from harmless and he was one of the more successful (and thus dangerous) antagonists of the story as he was the only assassin to play a major role in both parts of the story.
Taking on the guise of a salesman Norman feigned innocence and would lure his victims into a false sense of security by offering them free samples, only to kill them once invited into their home - although appearing human it was revealed that Norman was, in reality, an unearthly monster made out of thousands of insects working together.
Norman would spy on Buffy yet never made a move on her himself, being a much more cautious individual than the other assassins (a trait that arguably made him even more dangerous) - however he made a fatal mistake when he tried to kill Xander and Cordelia instead as the two, despite lacking supernatural power, managed to defeat the demon by using flypaper to trap the thousands of insects that made up his form and crushed them underfoot.