I enjoyed my deep dive into dullahans so much that I decided to look at the roots of another little-known folkloric beastie – namely, a supernatural creature by the name of Jimmy Squarefoot. Once again, Wikipedia has a disappointingly scanty article on the topic, so short that I may as well quote it in its entirety:
In Manx folklore, this is a legendary bipedal pig-headed creature living on the Isle of Man. He had two great tusks like a boar. It is generally a peaceful wanderer. His large feet are swathed in calico bands and are squarish in appearance. He is thought to have once been ridden by one of the Foawr, a race of stone-throwing giants. Jimmy Squarefoot is also the name of Monster in My Pocket #80 as well as a character in the 2007 PlayStation 3 video game Folklore.
The one source cited for this is Theresa Cheung’s Element Encyclopedia of the Psychic World, published in 2006. But thanks to Google Books I was able to find a number of much earlier attestations that allow a glimpse of how the figure of Jimmy Squarefoot evolved over time.