Mommet was a gray tabby cat owned by Cicily Sellis, a "cunning woman" in London. He was by her side, or on her shoulder, with curious frequency, and, unlike a typical cat, would come when she did call him. Numerous acquaintances of Sellis, including William Shakespeare and Lope de Vega, suspected that Mommet was a demonic "familiar" but were never able to confirm this to their satisfaction.