Bob (The Dresden Files)
Bob is a "spirit of intellect" who inhabits a skull perched on a shelf in Harry Dresden's secret lab. He is bound to the skull and its owner's wishes. He is free to leave the skull if given permission by his owner, but he will die if exposed to significant sunlight without a host body. His usual vessel is Harry's cat, Mister, who does not seem to mind Bob's presence.
As a spirit of knowledge, Bob has served various wizards over the years and functions much like a magical encyclopedia, assisting Harry with various tasks; such as making potions, preparing difficult rituals, and providing him with useful information about the various supernatural creatures Harry deals with throughout the books (since Harry's magic causes almost all modern technology to malfunction in his presence, he does not own a computer).
Although he frequently ribs Harry for being too stiff/noble, and he lacks a firm understanding of moral values, Bob is truly afraid of dark magic while under Harry's ownership. He panics when Harry shows him a drawing of one of the sigils for the Order of the Blackened Denarius and urges him not to confront the group. When he is asked to recall being owned by a powerful necromancer (having erased most related memories, and sealed away what he couldn't erase), he is reluctant to do so. Unlocking said memories changes him, making him arrogant and very powerful, and he nearly kills Harry, who saves himself only by tricking Bob into reverting to normal. Bob tends to be very stubborn about providing help unless Harry pays him, in the form of spicy romance novels and occasional time out of the skull. Harry is extremely reluctant to allow the latter, since these forays tend to have unfortunate consequences; for instance, Bob once "crashed" a party at a local college fraternity house, and ended up causing a full-blown orgy.
Bob's personality seems to be malleable, adapting to suit his current owner, and abiding by their wishes. When Bob is stolen by a necromancer, Bob advises the wizard against Harry's own interests, but is eventually convinced by Harry to betray his new owner and assist Harry instead. Harry later speculates that he was able to willingly do this because it was Harry who gave him his name.
Although Bob has no physical features of his own, appearing as a sort of orange cloud of light, he can create expressions within the skull, appearing as eyes of orange dots of light, which can roll and narrow and adjust to mimic human expressions. He can use the skull itself to express emotions, such as letting the jaw drop open in surprise (real or fake), or turning to bang the forehead against the wall in frustration.
Bob's character is significantly altered to give him a more prominent role in the TV series. His full name is Hrothbert of Bainbridge. A powerful sorcerer, he died in 900 A.D., apparently in England. During his career he authored many grimoires, the first of which fell into the hand of Justin Morningway, Harry's uncle. As Harry put it, there was "some pretty nasty stuff in there," including something called a "Doom Box." Harry burned Justin's copy after it came into his possession (episode 101, "Birds of a Feather"). During his life, Hrothbert fell in love with a woman, another skilled wizard (sorceress), by the name of Winifred. When she was tragically killed, he used black magic to resurrect her. For this he was condemned by the High Council to be a ghost trapped within his own skull for all eternity, unable to interact with the world in any physical way. According to the Morningway-doppelgänger, the story of Hrothbert and Winifred is legendary in some countries. Bob is still sensitive about the subject (episodes 106, "Soul Beneficiary;" 110, "What About Bob?").
Unlike the book version, Bob usually appears in his human form, only rarely disappearing inside his skull.
Bob first met Harry Dresden circa 1982, when the wizard, 11 years old and newly orphaned came to live with his uncle, Justin Morningway, who was in possession of Bob's skull at the time. Bob served as the boy's tutor in all things magical, teaching him the principles of black magic and the defense against it, and while practicing black magic is strictly forbidden by the High Council, Bob felt Harry ought to know it for "self defense". This comes into play years later when Harry, fully grown, comes back to his uncle's and discovers his father's ring and a voodoo doll. He asks his uncle if he killed his father, and Justin gives him a speech resembling a manifesto about how it's time for a change, and Justin and Harry can change things. Harry realizes that Justin didn't invite the High Council for a networking session to benefit Harry, but rather as a trap to exterminate them. Harry tries to stop him, but his uncle fights back. Bob sees Harry remove the voodoo doll but doesn't say anything, knowing, as Harry does, that if Harry were to press the ring around the voodoo doll's "heart," Justin would die as the ring has been in his possession long enough to be a personal item. When Justin summons a large shard of wood to try to thwart Harry, it is Bob who shouts out a warning, despite the fact that his skull is in Justin's possession. Justin dies when Harry's hand clutches in pain after being grazed by the shard of wood, and while Harry refuses the rest of the inheritance and gives it to charity (besides the house), he keeps Bob within his possession. Morgan, a Warden of the High Council, is opposed to Dresden's continued possession of the skull, believing that Bob is dangerous (episode 110, "What About Bob?").
Harry has since made a way for himself in Chicago, straddling the world of the everyday and the supernatural by acting as a private investigator and consultant for the Chicago Police Department on seemingly unexplainable cases, and Bob is his secret weapon in this. Not only does Bob contain a wealth of knowledge gleaned from his own wizardly expertise, the ghost has accumulated centuries of experience since being tied to his skull. In addition, Bob can take on the appearance of people given a piece of their personage, an ability that has proven essential to the happy resolution of several cases (episodes 103, "Hair of the Dog;" 104, "Rules of Engagement"). The ghostly wizard can also write in the air in glowing letters (episodes 101, "Birds of a Feather;" 106, "Soul Beneficiary").
To Harry, Bob is far more than a simple tool or resource; he is a friend and mentor, and both care deeply for each other. The ghost strongly affirms that he would never betray Harry, even though the opportunity has been presented more than once (episodes 101, "Birds of a Feather;" 106, "Soul Beneficiary;" 110, "What About Bob?"). When Bob's mortality is restored by a doppelgänger of Justin Morningway, in order to resurrect the original Justin using Bob's infamous black magic spell, Bob instead sacrifices his physical existence so as to destroy Morningway forever and ensure Harry's safety. As Bob is dying from the spell, Harry mourns him. Bob, however, simply reverts to his ghostly existence. (episode 110, "What About Bob?").
When Dresden is kidnapped by a pair of women planning on using him to commit insurance fraud, Bob faces a difficulty of how to effect any sort of rescue, seeing as he cannot travel far from his skull and cannot, due to his non-corporeal state, say, pick up the phone and call the police. Fortunately, Detectives Murphy and Kirmani end up coming to Harry's office, and Bob leaves a floating message in glowing letters for them, giving them the information they need to find the missing wizard (episode 106, "Soul Beneficiary"). While Bob may roll his eyes at Harry's "quixotic" desire to help people, he consistently assists Dresden, even if only by offering testy or critical advice.
Bob, though he tries not to let it on too much to Harry, suffers emotionally from his inability to physically affect the world, and he feels responsible when he is unable to stop a woman from getting murderously struck by a car just outside Harry's office. The feeling experienced by a living person when Bob inhabits the same space is quite unsettling. "That's something, at least," Bob mutters glumly (episode 107, "Walls"). He spends his spare time doing such things as redesigning old spells, such as the "Doom Box," something of a magical bomb, which Harry uses to destroy a skin walker (apparently sent by the Morningway-doppelgänger in episode 101, "Birds of a Feather"). Bob is also something of a romantic: he is seen with a handkerchief, wiping his eyes during a movie while a rather bored-looking Harry is watching with his latest girlfriend (episode 105, "Bad Blood"). He is also constantly interested in the physical attractiveness of the female clientele that come to Harry Dresden for help.