Thomas Sanders McMillan (November 27, 1888 – September 29, 1939) was a lawyer and a United States Representative from South Carolina. Born in the town of Ulmer in Allendale County, McMillan received his early childhood education at the schools in Ulmer. He graduated from the Orangeburg Collegiate Institute in 1907 and taught school for the next two years in Perry. McMillan then enrolled at the University of South Carolina and graduated in 1912. In 1913, he completed the law course at the university and was admitted to the bar the same year. He moved to Charleston where he began the practice of law on January 1, 1915, with James B. Heyward, as well as pursuing his agricultural interests.