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.

[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.

They are initially blind and only partially furred, and remain attached to the mother's teats for most of their first two weeks, although they are able to crawl from two days of age.