The males of the Vieillot's Black Weaver (Ploceus nigerrimus) are all-black. 
Females are olive-green with paler underparts. 
Both sexes have a pale eye: yellow in males and pale brown in females.
The Vieillot's Black Weaver occurs from South Nigeria to Uganda, West Kenya, Angola and the Democratic Republic of Congo.

The Chestnut-and-black Weaver (Ploceus castaneofuscus) the male of which has a chestnut-brown belly and back (not black) and that occurs in Sierra Leone to South Nigeria, was formerly considered to be conspecific with the Vieillot's Black Weaver but was split in 2022 based on the striking differences in the colour of the plumage.

st, 2nd & 3rd photo: A male. Botanical Garden, Entebbe, Uganda, 15 January 2025
4th photo: A male. Buhoma area, Bwindi National Park, Uganda, 19 January 2025
5th photo: A female. Guereza Canopy Lodge, Bigodi area, Kibale National Park, Uganda, 27 January 2025