Byron Emmerson Johnson (September 16, 1911 – September 24, 2005), also known as Mex Johnson, was a baseball player in the Negro leagues. His nickname came from a hat he wore as a child which looked like a sombrero. Born in Little Rock, Arkansas, United States, he began his Negro leagues career in 1937 as a shortstop with the Kansas City Monarchs and stayed with the Monarchs until his retirement in 1940. He also was on the road team the Monarchs called the Satchel Paige All Stars from 1939 to 1940.