The sooty barbthroat (Threnetes niger) is a hummingbird species in the family Trochilidae. It is found in Brazil and French Guiana.

The sooty barbthroat is 10 to 12 cm (3.9 to 4.7 in) long. The adult male has iridescent bronze-green upperparts and breast, a black ear patch and throat, and a pale malar stripe. The tail of the nominate subspecies is uniformly dark; that of T. n. loehkeni has pale tips to the feathers. The belly is dark brownish gray. It has a nearly straight bill. As with other hermit hummingbirds, the sexes are similar; the female's bill is somewhat more decurved than the male's and the plumage has less contrast among the throat, breast, and belly. Young birds resemble the adult but have ochraceous feather edges.