Reaper is the beloved pet cat of Agatha. Reaper is bald with scratchy ears. In the beginning of the book, Reaper tries to attack Sophie while she is on the porch talking to Agatha through her front door. Some readers, after reading The School for Good and Evil believe that Reaper could tell that Sophie was evil and wanted her off of Agatha's porch, but that hasn't yet been clarified by the author Soman Chainani. No one knows how old Reaper is.


Agatha's first friend was Reaper. Agatha's mother, Callis of Netherwood, raised the then kitten as her own cat, and Reaper was full grown when Agatha was born. Throughout the first book, Agatha thinks about Reaper, and deeply misses him. She eventually started to forget about her home life, specifically when she forgot his eye color. When Agatha returns home in the second book, Reaper acts like she's a stranger, because she acts 'different.' In the third book, when Agatha brings her prince, Tedros, home to Gavaldon, Reaper appeared to dislike Agatha even more because of her choice of mate, who disliked the cat heavily. Later, Reaper carried messages for the League of Thirteen, ascertaining that he seems to have intelligence beyond the average cat's. Agatha appears sad, claiming, "He used to love me." In Quests for Glory, he and Agatha seem to be on good terms again, as Reaper freely wanders around the castle.


Just like any other cat, Reaper's only real food source are the birds that fly into the graveyard. In the beginning of the story, Agatha states that 'Reaper's running out of birds' when the cat tries to attack Sophie, and it is later revealed that he hides headless bird corpses in Agatha's clothes.