John Alden Thayer (December 22, 1857 – July 31, 1917) was a Representative from Massachusetts. He was born in Worcester, Massachusetts. He was the son of Eli Thayer. He graduated from Harvard College in 1879. He studied law at Columbia Law School in New York City. He was admitted to the bar in 1889 and was a clerk of the central district court of Worcester from 1892 to 1897.