In early editions of the novel, they are shown as African pygmies. Following growing controversy and criticism, in later editions of the book, they are white skinned and golden haired.
They come from Loompaland, which is a region of Loompa, a small isolated island in the Pacific Ocean. The Oompa-Loompas would end up being preyed upon or attacked by Whangdoodles, Hornswogglers and Snozzwangers. Wonka ended up inviting them to work at his factory and get away from their natural enemies. In the book, they are the only people Willy Wonka will allow to work in his factory, because of the risk of industrial espionage committed by his candy-making rivals. They are only knee-high, with astonishing haircuts, and are paid in their favorite food, cacao beans. They insist on maintaining their native clothing: men wear skins, women wear leaves, and children wear nothing at all (In both movies, they wore typical factory worker uniforms). Only the male Oompa-Loompas are seen working in the factory, though in Quentin Blake's illustrations, both male and female Oompa-Loompas are shown rolling away Violet Buereguard after her transformation into a blueberry. Presumably the females remain in the village seen briefly from the Great Glass Elevator.
They are also mischievous, love practical funny jokes, and singing. As each bad child makes his/her exit, they sing moralizing songs accompanied by a drum beat. Some of the rhymes were amusing, but the parents of the bad kids did not find them as funny as Charlie and Grandpa Joe.
- In the 2005 film production of Charlie and the Chocolate Factory starring Johnny Depp, the Kenyan actor Deep Roy played all 165 Oompa Loompas. Deep Roy had to take Pilates and dance classes for this role which involves numerous songs and dances. Also, he was dressed as some female Oompa-Loompas that worked in the Administration Offices.
- In the 1971 film Willy Wonka & the Chocolate Factory, they are portrayed as orange skinned and were portrayed by Rudy Borgstaller, George Claydon, Malcolm Dixon, Rusty Goffe, Ismed Hassan, Norman McGlen, Angelo Muscat, Pepe Poupee, Marcus Powell, and Albert Wilkinson. In the film, Vermicious Knids were also the enemies of the Oompa-Loompas alongside the Whangdoodles, Hornswogglers and Snozzwangers.