Mr. Teatime is a BadassPsycho for Hire Assassin, who maintains a baseline level of awesome that is so high that Crowning Moments Of Awesome are less likely to show up against the background. It could be argued that his entire appearance is a Crowning Moment Of Awesome. Unless he's terror personified. Alternately, he could be both. Especially given his ability to find purchase on thin air and tickle someone with a knife through several layers of clothing.
The head Assassin calls for him at the start of the book. Then turns around to find him standing at the mantelpiece, petting the dogs. Teatime then scares the crap out of him over the course of the following few minutes. This sets your expectations for the character for the book, and he does not disappoint.
Death gets a small one, when he gets Teatime's name right. Thus impressing Teatime.
Death ruining Teatime's plan to pop up as a ghost...
Death's true Crowning Moment of Awesome comes in this book, at the very end, when, finally free from the constraints he had been forced to adhere to until the safety of the Hogfather was assured, he obliterates a huge number of Auditors. What really makes this more interesting is that you never actually see him do it, you simply hear his speech to them and witness the final sequence when he seems to grow larger before them and utter, Ho. Ho. Ho.
Have you been naughty...or nice? HO. HO. HO.
The film takes it another level by making it clear just how much Death is enjoying the moment. Yes, there are rules. And you broke them! How dare you? HOW DARE YOU? is infused with so much raw anger that you suddenly become very glad that he's on our side.
Death defies narrative tradition by saving the Little Match Girl, What better present than a future? indeed. Albert then gets a small one by throwing snowballs at angels who come to take the girl to heaven.
When Susan takes the fireplace poker—it's been imbued by the children's belief to defeat any monster, and to only hurt monsters—and throws the poker at her grandfather, the Grim Reaper; it passes through him and hits Teatime, the psychotic Big Bad. Because, after all, the poker only hurts monsters, and the children can see who the real monster is. And what makes it even more awesome is that she scared the crap out of grandpa in the process, and she didn't even know for sure if it would work.
And slightly before that, where she encounters the Scissor Man, the nightmarish thing that children are told will cut off their thumb if they suck on it. It's described as looking less like a man and more of an ostrich or lizard made of blades. And she intimidates it.
'I remember you came for Twyla,' said Susan, stepping forward. 'That damn governess had told her what happens to little girls who suck their thumbs, remember? Remember the poker? I bet you needed a hell of a lot of sharpening afterwards...' The creature lowered its head, stepped carefully around her in as polite a way as it could manage, and clanked on down the stairs after Peachy.