Dennis is a census-designated place and unincorporated community located at the intersection of Mississippi Highway 25 and Mississippi Highway 4 in Tishomingo County, Mississippi, United States. Dennis is approximately 6 miles south of Tishomingo and 3 miles north of Belmont. Although an unincorporated community, Dennis has a post office. It was first named as a CDP in the 2020 Census which listed a population of 172.