Tombaatar is a mammal genus that existed during the Mongolian Upper Cretaceous period. It co-existed with some of the late dinosaurs. This animal was a member of the extinct order Multituberculata, within the suborder Cimolodonta and family Djadochtatheriidae. The genus Tombaatar was named by Rougier G.W., Novacek M. and Dashzeveg D. in 1997.