Leeroy Thornhill (born 7 October 1969, Barking, East London) is an English electronic music artist and formerly a rave dancer and occasionally keyboardist for the British breakbeat band The Prodigy. He is an international inspirational dance legend, known worldwide as 'The Prodigy Dancer.' Leeroy is a master shuffler and one of the great innovators of 'The Running Man' dance step, which he developed and took to the next level after first studying James Brown, and later Rosie Perez in the opening credits of Spike Lee’s 1989 film Do The Right Thing. His style of dance can be described as a 'technical running on the spot'. This style of dance has reportedly had a major influence in the development of the Melbourne Shuffle underground rave dance style, and thus Leeroy Thornhill was interviewed for the underground dance documentary Melbourne Shuffler to talk about his dancing.

He has produced solo work under the names Longman and Flightcrank. He was born in Barking but raised in Rayne near Braintree in Essex, and grew up as a football and James Brown fan. Thornhill joined The Prodigy along with Keith Flint and Maxim Reality after they met Liam Howlett at a local rave club. Both were dancers for the band's live show. Thornhill's height is 6-foot 7 inches (200 cm), a whole foot taller than Flint who is 5-foot 7 inches (170 cm). In 2000 Thornhill left the band and went on to record various EPs under the guises of Longman and Flightcrank, however these projects never saw any substantial success. He now DJs at large venues and is still in touch with The Prodigy. During The Prodigy's 'Their Law' tour Thornhill was the DJ support act at several venues. He also works as a regular DJ. He also remixed tracks for other artists, such as the Italian Subsonica's Nuvole Rapide.

Thornhill is currently working with Hyper and appears on their live shows. He appeared at the V Festival in 2007 in Chelmsford, Essex.

His latest project is the creation of Nu skool breaks record label Electric Tastebuds. He has recently signed breakbeat act The Wrongstar Society to the label.

In October 2008, a music video was created for "Everything U Need", a track by Thornhill's Smash Hi-Fi project. The video was Directed by Philip Carrer and Bleeding Apple.