John Thomas is the name of:

A politician:

• John Chew Thomas (1763-1836), US Congressman from Maryland ^*
• John L. Thomas, Jr. (1835-1893), US Congressman from Maryland ^*
• John Robert Thomas (1846-1914), US Congressman from Illinois ^*
• John Thomas (senator) (1874-1945), US Senator from Idaho ^*
• John W. Elmer Thomas (1876-1965), US Senator from Oklahoma ^*
• John Parnell Thomas (1895-1970), US Congressman from New Jersey

A religious figure:

• John Thomas (Christadelphian) (1805-1871), founder of Christadelphianism
• John Roland Lloyd Thomas (1908-1984), Anglican clergyman
• John Thomas (preacher), Welsh Methodist preacher
• John Christopher Thomas, Pentecostal theologian
• John Thomas (bishop of Lincoln), former bishop of Lincoln and Salisbury
• John Thomas (bishop of Peterborough), former bishop of Peterborough
• John H. Thomas, President and General Minister of the United Church of Christ

An academic figure:

• John Martin Thomas (1869-1952), twelfth President of Rutgers University
• John Thomas (dean), 18th century dean of Westminster Abbey

A military figure:

• John Thomas (general) (1725-1886), American general in the American Revolutionary War
• John Thomas (VC), recipient of the Victoria Cross

An athlete:

• John Thomas (basketball), basketball player
• John Thomas (high jumper), one-time record-holding high jumper
• John Thomas (NFL player), lineman for San Francisco 49ers

An artist:

• John Thomas (sculptor), British sculptor who worked on Buckingham Palace and the Palace of Westminster

A musician:

• John Thomas (harpist) (1826-1913), Welsh composer and musician
• John Thomas (trombonist) (1902-1971), trombone player who worked with Louis Armstrong
• John Thomas (singer), 1950s Antiguan benna singer

A writer:

• John Thomas (author): A Springburn, Glasgow, born author of railway books mostly published by David and Charles
• John Thomas (screenwriter): co-screenwriter (with his brother) for the movie Predator
• John E. Thomas: American author of children's books

A harp maker:

• John Weston Thomas: Founder of modern Welsh harp making

In the UK, John Thomas is sometimes used as a euphemism for the penis; the term was used as such in Lady Chatterley's Lover.