Calephelis nemesis (fatal metalmark or dusky metalmark) is a butterfly in the family Riodinidae.

It is found in the southern part of the United States and Mexico.

[2] Its habitats include chaparral canyons near rivers in arid areas, roads, and washes.

The larvae feed on Encelia californica, Baccharis glutinosa, Clematis drummondii and Clematis henryi.

This Riodinidae-related article is a stub.