A grimalkin is a house cat, generally but not always female. Grimalkins are often the familiars of witches, so the presence of this particular cat (especially with Matthew Maule as context) brings to mind devils and black magic. This grimalkin is a large animal with a "very ugly look" (18.23) who crosses the garden in Chapter 16 – the chapter when Judge Pyncheon dies. He also appears to look in through the window at Judge Pyncheon's dead body in Chapter 18. The narrator asks, "Is it a cat watching for a mouse, or the devil for a human soul?" (18.23). The presence of this cat ratchets up the gloomy, supernatural atmosphere of these chapters of the novel.