Glen Allan is a census-designated place and unincorporated community located in far southern Washington County, Mississippi. It is situated immediately east of Lake Washington's southern shore.
It has a post office, with the ZIP code 38744.
It was first named as a CDP in the 2020 Census which listed a population of 298.
Glen Allan is served by the Western Line School District. The elementary schools are O'Bannon Elementary and Riverside Elementary. The High Schools are O'Bannon High and Riverside High School.
Glen Allan is the birthplace of author Clifton Taulbert and blues guitarist/singer songwriter Robert Lee "Smokey" Wilson, and Keith Johnson aka Prince of the Delta Blues. He is also the great nephew of blues icon Muddy Waters.