Spring-heeled Jack was a humanoid Abnormal with supernatural jumping abilities.
He preyed on humans in southern England of the Victorian era, who in turn hunted him. Dr. Helen Magnus was eventually able to convince him to come and live with her and James Watson in the safety of the UK Sanctuary; he was, in fact, its first inhabitant. 
"Spring-heeled Jack" is a character in English Victorian folklore, known for his startling jumps. The first claimed sighting of him was in 1837. Later sightings were reported all over England and were especially prevalent in suburban London, the Midlands and Scotland.