Perhaps one of the greatest achievements in The Graveyard Book is how believable the characters are. It is a tribute to Neil Gaiman's strength as a writer that he creates such convincing characters, many of whom are residents of the graveyard.
Consider one of the occupants, Liza Hempstock, who was nearly drowned and then burned for being a witch. She is frustrated that she lacks a grave marker, feelings she shares with Bod in their first meeting. “ It’s not much to ask, is it? Something to mark my grave. I’m just down there, see? With nothing but nettles to show where I rest.’ And she looked so sad, just for a moment, that Bod wanted to hug her.”
He hatches a plan to make her a head stone, and Liza comes to his rescue when he is entrapped in a pawn shop he visits to collect money to make her one.
In Potter’s Field, he leaves a paperweight with her initials. “We don’t forget,” it says.
Liza approves. “‘ Not bad,’ said a pert voice from the Potter’s Field behind him. ‘Not bad at all.’”
A similar case for the authenticity of virtually all of the characters could be made.