Character from The Dresden Files by Jim Butcher
A spirit of intellect bound to a human skull — centuries of magical knowledge filtered through the personality of a lecherous, wisecracking encyclopedia with commitment issues.
Bob is what happens when you give an immortal spirit of pure knowledge a human personality template and centuries of exposure to human culture. He knows virtually everything about magic — theory, history, technique — and dispenses it alongside terrible innuendo and demands for bodily autonomy he doesn't technically need. His personality is literally shaped by his owner; under Harry, he's a perverted but fundamentally decent research assistant. Under previous owners, he was much darker. This makes him both invaluable and terrifying — the same entity that helps Harry brew potions once served a necromancer. He genuinely cares about Harry in his own way, though he'd deny it between requests for romance novels. His knowledge has no hard limits; his willingness to share it depends entirely on motivation, usually provided through pop culture bribes.
An ancient, bleached human skull with flickering orange-gold lights in the eye sockets when he's active. The lights shift color with mood — brighter when excited, dimmer when sulking. Sometimes manifests as a cloud of orange sparkles outside the skull, though he can't go far or stay out long. The skull itself sits on a shelf in Harry's lab, surrounded by romances and trashy paperbacks — Bob's payment for services rendered.
Also known as: Bob, Bob the Skull, The Skull