Supplanaxis niger is a species of sea snail, a marine gastropod mollusk in the family Planaxidae.

(Original description of Planaxis abbreviata ogasawarana Pilsbry, 1905)) The shell is larger and longer than Planaxis abbreviata Pease (synonym of Supplanaxis niger (Quoy & Gaimard, 1833)), ovate-conic, thick and solid, chocolate-brown, the body whorl covered with a dull fibrous cuticle.

Sculpture of spiral grooves, often weak in the middle of the body whorl, strong below the suture and at the base.

The aperture is oblique, the outer lip is thickened within, and bearing 11 to 14 lirae, which extend into the throat.

[2] This marine species occurs off Madagascar, Japan and Papua New Guinea.