Ottertail is a city in Otter Tail County, Minnesota, United States. The population was 572 at the 2010 census.
According to the United States Census Bureau, the city has a total area of 5.10 square miles (13.21 km2), of which 4.28 square miles (11.09 km2) is land and 0.82 square miles (2.12 km2) is water.
Minnesota State Highways 78 and 108 are two of the main routes in the community.
Ottertail was platted in 1903, and named for nearby Otter Tail Lake.
As of the census of 2010, there were 572 people, 245 households, and 171 families living in the city. The population density was 133.6 inhabitants per square mile (51.6/km2). There were 401 housing units at an average density of 93.7 per square mile (36.2/km2). The racial makeup of the city was 99.0% White, 0.2% Native American, and 0.9% from two or more races. Hispanic or Latino of any race were 0.9% of the population.
There were 245 households of which 22.0% had children under the age of 18 living with them, 57.1% were married couples living together, 9.4% had a female householder with no husband present, 3.3% had a male householder with no wife present, and 30.2% were non-families. 24.9% of all households were made up of individuals and 8.6% had someone living alone who was 65 years of age or older. The average household size was 2.33 and the average family size was 2.75.