Vivien Theodore Thomas (August 29, 1910 - November 26, 1985) was an African-American surgical technician who helped develop the procedures used to treat blue baby syndrome in the 1940s. He was an assistant to Alfred Blalock at Vanderbilt University in Nashville, Tennessee and later at the Johns Hopkins University in Baltimore, Maryland. Without any education past high school, Thomas rose above poverty and racism to become a cardiac surgery pioneer and a teacher to many of the country's most prominent surgeons. Thomas was born close to Lake Providence, Louisiana. The son of a carpenter, he attended Pearl High School (now known as Martin Luther King Magnet High School for Health Science and Engineering) in Nashville, Tennessee, in the 1920s. Even though it was part of a racially segregated system, the school provided him with a high-quality education. Later, when Thomas' savings were wiped out, he abandoned entirely his plans for college and medical school, relieved to have even a low-salary job as the Great Depression deepened.

Thomas showed an extraordinary aptitude for surgery and precise experimentation, which led Blalock to grant him more freedom in the execution of the procedures. Tutored in anatomy and physiology by Blalock and his young research fellow (Dr. Joseph Beard), Thomas rapidly mastered complex surgical techniques and research methodology. He and Blalock developed great respect for one another, forging such a close working relationship that they came to operate almost as a single mind. Outside the lab environment, however, they maintained the social distance dictated by the norms of the times. In an era when institutional racism was the norm, Thomas was classified, and paid, as a janitor, despite the fact that by the mid 1930s he was doing the work of a postdoctoral researcher in Blalock's lab.