Sumichrast's vesper rat (Nyctomys sumichrasti) is a rodent of the family Cricetidae found from southern Mexico to Panama.

It is named for François Sumichrast, the collector of the first specimen, and its closest relative is probably Hatt's vesper rat, a similar, but slightly smaller, species from the Yucatán Peninsula.

The rats have a thick pelt of soft fur, which extends over the entire length of the tail, and is absent only on the soles of the feet.

The eyes are relatively large, and surrounded by a narrow ring of black hair, while the whiskers are long and the ears small.

[3] A total of nine subspecies are currently recognised:[3] Sumichrast's vesper rat is unusual in that it is arboreal, and builds nests of twigs and leaves.