Etna is a census-designated place (CDP) in Lincoln County, Wyoming, United States. The population was 164 at the 2010 census.
Etna is located at 43°2′0″N 111°0′58″W (43.031124, -111.016042). in Star Valley, a grassland valley surrounded by forested mountains.
According to the United States Census Bureau, the CDP has a total area of 2.0 square miles (5.1 km²), all of it land.
At the 2000 census there were 123 people, 44 households, and 34 families in the CDP. The population density was 62.8 people per square mile (24.2/km²). There were 55 housing units at an average density of 28.1/sq mi (10.8/km²). The racial makup of the CDP was 93.50% White, 1.63% African American, 1.63% from other races, and 3.25% from two or more races. Hispanic or Latino of any race were 4.88%.
Of the 44 households 45.5% had children under the age of 18 living with them, 65.9% were married couples living together, 9.1% had a female householder with no husband present, and 20.5% were non-families. 15.9% of households were one person and 13.6% were one person aged 65 or older.