A grimalkin is an old or evil-looking female cat. The term stems from "gray" (the color) plus "malkin", an obsolete term for a cat, derived from the hypocoristic form of the female name Maud. Scottish legend makes reference to the grimalkin as a faery cat which dwells in the highlands.
The term/name may first come from Beware the Cat (published 1570) by William Baldwin , who relates the story of Grimalkin's death. According to its editors, the story, and thus the name, originates with Baldwin. It is also spelled Grimmalkin or Grimolochin.
During the early modern period, the name grimalkin - and cats in general - became associated with the devil and witchcraft. Women tried as witches in the 16th, 17th and 18th centuries were often accused of having a familiar, frequently a grimalkin.
Grimalkin was the name of the cat of Nostradamus, and later the witches' cat "Gray-Malkin" in Macbeth by William Shakespeare.
In Tom Jones, Henry Fielding relates a story from a 17th-century collection of fables in which Grimalkin is a cat whose owner falls passionately in love with her. He prays to Venus, who changes the cat into a woman. Lying in bed, however, she spots a mouse and leaps up after it, "Puss, even when she's a Madam, will be a mouser still."
In Wuthering Heights by Emily Brontë, Mr. Lockwood shares a set of two benches in the back kitchen of Healthcliff's manor with a Grimalkin described as a "brindled, grey cat, which crept from the ashes, and sluted me with a querulous mew."
Nathaniel Hawthorne, in The House of Seven Gables, Ch. XVI, mentions "...a strange grimalkin... was seen by Hepzibah while she was looking into the back-yard garden for Clifford." In the next sentence he gives definition to grimalkin as "...this cat seemed to have more than ordinary mischief in his thoughts,..."
The Godolphin Arabian, one of the stallions that helped found the line of Thoroughbred racing horses, was very close to a companion cat called Grimalkin. (Racehorses tend to be very high-strung and nervous animals, and often form a close bond with a companion animal; the tactic of trying to sabotage a race by abducting a racehorse's companion animal the night before the race is thought to have given rise to the term "getting someone's goat.")
In the television show "Batman", and later "The New Adventures of Batman", Catwoman (played by Eartha Kitt) operated the Grimalkin Novelty Company, at the corner of Cattail Lane and Nine Lives Alley.
In the 2008 series "Power Rangers: Jungle Fury", the pizza parlor Jungle Karma Pizza, which serves as a social hangout for the show's main cast, houses a pinball machine going by the name Grimalkin Gauntlet.
The governess/witch in the novel The Midnight Folk by John Masefield has two familiars named Greymalkin and Blackmalkin.
A grimalkin is briefly mentioned in The Dream-Quest of Unknown Kadath by H.P. Lovecraft, in which sentient cats play a major role.
In the Wardstone Chronicles, written by Joseph Delaney, Grimalkin is the name given to the assassin witch of the Malkin family.
In Jim Butcher's novel Small Favor, a large cat named Grimalkin appears with Mab, Winter Queen of the Faeries.
Grimalkin is used by Mab as a surrogate voice for an unknown reason. It is suggested that he belongs to a species of such cats known as malk.
In the video game BlazBlue: Calamity Trigger when Hakumen is defeated as the sub-boss of the game for all default characters (not counting Jin, the aforementioned Hakumen himself, and v -13-), he is suddenly warped out of the battlefield, all the while angrily yelling, "How dare you interrupt me, Grimalkin!" When he says that, he is referring to his mistress, Kokonoe. The Grimalkin in BlazBlue is a species of cat-like people, with three known Grimalkins being Taokaka, the aforementioned Kokonoe, and the original Grimalkin, Jubei.
In Gregory Maguire's novel A Lion Among Men, the cowardly lion, Brrr, has a "glass cat" companion who is later discovered to be named Grimalkin.
Thank you wikipedia