Southmayd (the latter syllable pronounced like "maid") is a city in Grayson County, Texas, United States.

Southmayd is located in central Grayson County along Texas State Highway 56.

Texas State Highway 289 runs north–south through the eastern part of the city.

14.3% of all households were made up of individuals, and 5.0% had someone living alone who was 65 years of age or older.

Southmayd is served by the S and S Consolidated Independent School District.