The Blond Haired Security Guard was a security guard seen in the episode "Trapper Keeper".
In "Trapper Keeper", he along with Mark the Security Guard, were stationed at Cheyenne Mountain's military base. He, and many other people, couldn't tell Rosie O'Donnell apart from the Cartman/Trapper Keeper blob. He survived the disaster.
He also appeared in "Korn's Groovy Pirate Ghost Mystery", where he was seen warning South Park about Cleo Broflovski's stolen corpse. He mentions that is had been stolen, for the purpose of having sex with it. Unbeknownst to him, the boys had dug it up to scare the 6th Graders. In addition to warning about the stolen body, they also go into graphic detail of what necrophilia is and how it is performed.
As his name suggests, he has blond hair. He wore a blue shirt, black tie, blue pants, a black belt with a gold buckle, and large, square, black-framed glasses.
He appears to be of relatively low intelligence, not realizing how dangerous the Cartman/Trapper Keeper hybrid was despite its grotesque, ominous appearance.