Exploring the vast urban legend surrounding this enigmatic figure, John Matthews explains how the Victorian fascination with strange phenomena and sinister figures paired with hysterical reports enabled Spring-Heeled Jack to be conjured into existence. Sharing original 19th-century newspaper accounts of Spring-Heeled Jack sightings and encounters, he also examines recent 20th and 21st-century reports, including a 1953 UFO-related sighting from Houston, Texas, and disturbing accounts of the Slender Man, who displays notable similarities with Jack. He traces Spring-Heeled Jack's origins to earlier mythical beings from folklore, such as fairy creatures and land spirits, and explores the theory that Jack is an alien marooned on Earth whose leaping prowess is attributed to his home planet having far stronger gravity than ours.