Ennis is a town in Madison County, Montana, United States, in the southwestern part of the state. The population was 838 at the 2010 census.
U.S. Route 287 runs through town, following the Madison River as it descends from the town of West Yellowstone.
In 1863, gold was discovered in Alder Gulch. This brought on "the rush." Two months later, William Ennis homesteaded the site along the Madison River that was soon to become the town of Ennis, his namesake.
In 1886 a mystery creature was noted for making livestock kills in the Madison Valley. A local rancher Israel Ammon Hutchins finally shot & killed the beast, after accidentally shooting one of his cattle, which was on the other side of some brush. A local taxidermist stuffed the canine. Jack Kirby (Hutchins' Grandson) tracked the mount to a Museum in Pocatello, Idaho, around 2007.
Avid Aircraft, a manufacturer of homebuilt aircraft, was located in Ennis. The company ceased operations in 2003.
The 2003 Ennis shooting occurred on June 14, 2003, when 44-year-old, George Harold Davis, opened fire outside the Silver Dollar Saloon bar on Main Street.