The red-headed trogon (Harpactes erythrocephalus) is a species of bird in the family Trogonidae.
The red-headed trogon is on average 34 cm in length. The male has a red head and breast, a unique feature in the Trogon group. The female resembles the Diard's trogon without a speckled undertail.
The head, neck and upper breast of an adult male is dull crimson. A narrow white band crosses the mid breast, underneath which the lower breast to abdomen is light red to pink. Pale red can be observed on the flanks whereas the mantle and back of the bird are rusty brown. The male perches on branches with the support of mauve-blue legs. Regarding wing colouration, the lesser and median wing coverts, secondary coverts, as well as outer webs of tertials and secondaries are vermiculated black and white. The primary feathers also appear black and white. As for the bird's long tail, the central feathers are dark brown with a black tip, the second and third pairs are black and the outer pairs are white with black bases. Finally, a black-tipped cobalt blue bill, a deep mauve-blue gape and eyering and reddish-brown irises shape the bird's face.
The head, neck and upper breast of an adult female are olive-brown. Just like the male, a narrow white band crosses the mid breast, underneath which the lower breast to abdomen is light red to pink. The mantle and back appear orange to brown in colour. The wings are vermiculated dark brown and yellowish brown. The tail feathers are very similar to those of the males. The bill, gape and bare eyering are pale blue on females.
At the juvenile stage, the head, neck and upper-parts are buff brown, whereas the underparts appear buff white. No black tip on the narrower central tail feathers can be observed.