Anvilicious: Death's speech to Susan about how humans need fantasies like the Hogfather (i.e. Santa Claus), or Terry Pratchett's books for example, to believe in when they're young so that when they grow up, they can believe in big fantasies like justice, mercy and... purpose.
Complete Monster: Jonathan Teatime is a sadistic assassin feared even amongst hardened criminals. Implied to have killed his own parents, Teatime has a penchant for excessive slaughter. In one instance, Teatime nailed his target's pet dog to the ceiling for barking too much and killed his servants because he didn't want them to barge in on him. After the Auditors hire Teatime to kill the Hogfather, Teatime abducts a tooth fairy to use her magic to break into the country of the Tooth Fairy, stealing all the teeth of all the children in the Discworld to use Sympathetic Magic to force all the children to stop believing in the Hogfather in order to kill him, causing a void in Ankh-Morpork's magic that wreaks havoc in the process. Teatime, unlike other members of the Assassins' Guild, shows no regard for the lives of civilians or his own men, in one instance killing a stagecoach driver out of boredom while chatting with him and in another instance having a locksmith working for him dropped down a long spiral staircase to a painful death when he's no longer useful. When Death and Susan foil his assassination attempt, Teatime tails them to the nursery Susan works at in an attempt to kill Death.
Ensemble Dark Horse: Teatime is quite the popular character among fans, despite only appearing in this one book.
Genius Bonus: Many of the computer references made towards Hex. In particular the teddy bear being removed might be a reference to the Microsoft Teddy Bear which was used as the icon for a vital file in the early windows OSs. Many users (helped by an email hoax) mistook the strange file for a virus and deleted it, with disastrous consequences.
Iron Woobie: Death. A recurring theme from his own Myth Arc, true, but it's especially visible when you see just how much he prefers giving presents to the living instead of guiding the dead.
Magnificent Bastard: The Tooth Fairy is in truth the original Bogeyman born from ancient man's primordial fear of the dark. Taking pride in terrorizing mankind, the Bogeyman became enraptured by the innocence of children and sought to protect them from the real monsters in life. He establishes a new identity as the Tooth Fairy and builds a vast franchise funded by property development to collect teeth to prevent them from being magically used against children. When psychopathic assassin Johnathan Teatime and his hired goons invade to use teeth to stop belief in the Hogfather, he uses the last of his power to conjure their worst nightmares to aid Death's granddaughter Susan and hunts the men down and brutally murders them even as they try to escape. Content with Susan's iron will and morals, the first Bogeyman fades away trusting her to ensure his mission is carried on.
Nightmare Retardant: In-universe. Gawain and Twyla don't find Death scary, thus not identifying him as a "monster", partially because he's on a big comfy chair and eating a biscuit.
Poor Bilious. Sure, we don't feel quite as sorry for him as we do for, say, Rincewind, but the poor guy gets all the hangovers from the god of wine without ever getting to actually enjoy earning them.
There is a chance that since adult concepts such as death do not exist in the Tooth Fairy's world, then hangovers might not exist either.
Except Bilious gets queasy again just as he and Susan enter the building. If anything, alcohol may cause instant nausea there, for the same reason that the mooks couldn't smoke inside without feeling ill: because that's how a little kid who's sneaked into the drinks cabinet and tried some would feel.
The Cheerful Fairy. The Senior Wrangler, at least, falls for her because of her Woobie-ness. Then he becomes a Woobie when she vanishes just before he was about to get serious with her.
Can't Un-Hear It: Regardless of your opinion on the TV adaptation, Michelle Dockery and Marc Warren's performances as, respectively, Susan Sto Helit and Jonathan Teatime are probably going to be definitive.
Complete Monster: Jonathan Teatime, a deeply disturbed psychopath in tune with his "inner child", is hired by the Auditors of Reality to assassinate the Hogfather. With a massive reputation of sadism and brutality already left in his wake, Teatime happily murders a coach driver out of sheer boredom, before breaking into the Tooth Fairy's castle and murdering the many guards to gain access to the teeth of all the children of the world. Teatime uses these teeth for a spell to kill the Hogfather by making children stop believing in him, while casually threatening his gang of hired mooks into continuing to help him. Upon killing his gang's lockpicker by throwing him down the castle's stairs when he outlives his usefulness, Teatime cheerily attempts to murder Susan for her interference, later trying to repeat the process with her and her grandfather in front of her young charges.
Foe Yay Shipping: Between Susan and Teatime. Apparently based on the confrontation scene in the Tooth Fairy's home which, with the right sort of squinting, can come across as sexual tension.
Albert's Your Days Are Numbered situation if you look at the German dub. His voice actor, Eberhard Prüter, had died of a long-term illness at the age of just 69 in October 2014.
which was used as the icon for a vital file in the early windows OSs. Many users (helped by an email hoax) mistook the strange file for a virus and deleted it, with disastrous consequences.