Jacques Collin de Plancy’s 1818 book Dictionnaire Infernal contained a list of demons, part of a long tradition of grimoires and demonology texts like the Pseudomonarchia Daemonum (1577) and the Lesser Key of Solomon (mid-17th century).
Alongside some well-known demons – Astaroth, Belphegor, Mammon, and Lucifer – the infernal dictionary included Wall (the camel demon!), Furfur (the deer demon!), and Leonard (the party demon!).
What made this text stand out were the illustrations: the 1863 edition contained pictures of Behemoth (a bipedal elephant):
Moloch (a cow-headed king):
Bael (a spider with the head of a man, a frog, and a cat):
… and sixty-six others.