Jack-In-Irons is a mythical giant

Giant (mythology)

The mythology and legends of many different cultures include monsters of human appearance but prodigious size and strength. "Giant" is the English word commonly used for such beings, derived from one of the most famed examples: the gigantes of Greek mythology.In various Indo-European mythologies,...

 of Yorkshire

Yorkshire

Yorkshire is a historic county of northern England and the largest in the United Kingdom. Because of its great size in comparison to other English counties, functions have been increasingly undertaken over time by its subdivisions, which have also been subject to periodic reform...

 lore who haunts lonely roads. He is covered with chains and wears the heads of his victims. He wields a large, spiked club

Club (weapon)

A club is among the simplest of all weapons. A club is essentially a short staff, or stick, usually made of wood, and wielded as a weapon since prehistoric times....

. His name may not be Jack as other Yorkshire folklore refers to "Jack-of-Green" and more so the name Jack may just be a term for calling the person an unknown male, like John Doe today.

In Popular Culture

Jack-in-Irons serves as the primary antagonist in a two 8-page comic story arc written by Robert James Russell and Jeff Pfaller, and drawn by Dan MacKinnon. The giant is disturbed by some local townsfolk blasting for coal, and goes on a rampage before two famed occult hunters attempt to bring him down. Published in 2010 by Saint James Comics

Saint James Comics

Saint James Comics is an American independent comic book publisher based in Detroit, Michigan. It was founded in 2009 by Robert James Russell and Jesse Young with the goal of publishing the sorts of comics they enjoyed reading themselves.-List of titles:...

.

Jack-in-Irons portrayed in the Merry Gentry series by Laurell K. Hamilton. Described as about 13 feet tall with mostly human features but the face (with large tusks) of a boar. His name is Uther.