Trioceros johnstoni, known commonly as Johnston's chameleon, Johnston's three-horned chameleon, and the Ruwenzori three-horned chameleon, is a species of chameleon, a lizard in the family Chamaeleonidae. The species is endemic to highlands in the Albertine Rift in central Africa. It reaches up to 30 cm (12 in) in total length (including tail). Only the adult male has three horns. The female is hornless.

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