Kilby Butte Colony is a Hutterite community and census-designated place (CDP) in Musselshell County, Montana, United States. It is in the center of the county, on the south side of U.S. Route 12, east of Roundup, the county seat. It is on the north side of the Musselshell River, an east-flowing tributary of the Missouri River.
The community was first listed as a CDP prior to the 2020 census. At the 2020 census, the population was recorded as zero.
According to the U.S. Census Bureau, the area of the CDP is , all land. The unincorporated community of Gage is to the west on US 12.