Reo is an unincorporated community and census-designated place in Ohio Township, Spencer County, in the U.S. state of Indiana.
The name Reo was coined in 1966 as an acronym of three nearby larger cities: Rockport, Indiana, Evansville, Indiana, and Owensboro, Kentucky.
South Spencer High School and South Spencer Middle School are located in Reo.
Reo is concentrated around the intersection of State Road 66 and State Road 161, a few miles northwest of the Ohio River.
The United States Census Bureau defined Reo as a census designated place in the 2022 American Community Survey.