128 Nemesis is a large 180 km main-belt asteroid, of carbonaceous composition.

[3][9] Nemesis is the largest member of the Nemesian asteroid family bearing its name.

It was discovered by J. C. Watson on 25 November 1872,[3] and named after Nemesis, the goddess of retribution in Greek mythology.

This object is orbiting the Sun with a period of 4.56 years and an eccentricity (ovalness) of 0.13.

It is categorized as a C-type asteroid,[10] indicating a primitive carbonaceous composition.