The Slaty-tailed Trogon, Trogon massena, is a near passerine bird in the trogon family, Trogonidae. It breeds in lowlands from southeastern Mexico south through Central America, to Colombia, and a small region of northwestern Ecuador.

It is a resident of the canopy and higher levels of damp tropical forests, but comes lower in adjacent semi-open areas. It nests 3 to 15 m high in an occupied termite nest or decaying tree trunk, with a typical clutch of three white or bluish-white eggs laid in a chamber reached by an ascending tunnel. Both sexes excavate the nesting chamber.

Slaty-tailed Trogons feed on insects and fruit, and their broad bills and weak legs reflect their diet and arboreal habits. Although their flight is fast, they are reluctant to fly any distance. They typically perch upright and motionless.

Trogons have distinctive male and female plumages, with soft, often colourful, feathers. This species is about 30 cm long and weighs 145 g. It has a uniformly dark grey tail, and the wing coverts also appear grey, although actually finely vermiculated in black and white. The male Slaty-tailed Trogon has a green back, head and breast, red belly and orange bill. The female has a dark grey back, head and breast, red belly and only partially orange bill, most of the upper mandible being black. The call is a nasal uk uk uk.