Nastra lherminier, the swarthy skipper, is a species of grass skipper in the butterfly family Hesperiidae. It is found in Central America and North America.
The upperside of the wing is dark brown. The forewing may have 2 very faint light spots. The underside of the hindwing is yellow-brown with lighter veins. The wing span ranges from 1 to 1.8 inches long or 2.5 to 2.9 centimeters long.