I gotta go with the Scottish/Irish Bartender for Favorite NPC. You know the guy, every DM everywhere uses him. 99% of the time the players never ask his name so he rarely ever needs one. And every single DM can do the voice. Its a cross between an angry Sean Connery and that one Blacksmith from Diablo 2.
"Whut can I do fer ya?!"
Sometimes he's a dwarf, sometimes he's a human, but he's definitely always bald, and always at least has a mustache (if not full beard). Depending on how much I want to move the players along, and how creative I'm feeling, he could also run the Inn, the Blacksmith shop, and the General Store. Basically, this guy can be found wherever things need to be purchased in a town. One-stop shop merchant for every lazy DM everywhere.