Dennis is a city in Parker County, Texas, United States. On May 6, 2017, voters approved incorporation of Dennis. On September 20, 2022, the U.S. Census Bureau notified the Geographic Names Information Service of the upgrade to city status. It has a post office, with the ZIP code of 76439. N. M. Dennis, a local judge, founded the community at the spot of a bridge across the Brazos River in 1892. The community's post office was opened in 1895. Today, FM 1543 passes through the community.