Gravelings are mischievous gremlin-like creatures that cause the accidents and mishaps (in the form of Rube Goldberg machine scenarios) that kill people. The living generally cannot see them, though in the episode "Reaper Madness", a schizophrenic was able to, although Rube refused to believe that was possible. Reapers can see and interact with them to some extent: Daisy once shushed a graveling; Rube yelled, "Get outta here!" once when seeing gravelings desecrating a cemetery statue; and George once chased several angry gravelings around her apartment. Although gravelings seem to be self-aware and recognize the reapers, they do not communicate verbally with them, and talk to each other in a hushed and unintelligible babble; other times they growl or hiss.