Nemegtbaatar is a genus of mammal from the Upper Cretaceous Period of what is now Mongolia. It existed in the company of much larger dinosaurs, found together in the Nemegt Basin. This creature was a member of the extinct order Multituberculata. It is within the suborder Cimolodonta and is a member of the superfamily Djadochtatherioidea. Nemegtbaatar was a relatively large member of Djadochtatherioidea, with a skull length of up to 4.5 cm. At least one specimen is in the Institute of Paleobiology collection of the Polish Academy of Science at Warsaw, (ZPAL MgM-1/76).