Who didn't serve two terms as president?

Several U.S. presidents didn't serve two terms, including notable figures like James K. Polk, who chose not to seek re-election after his first term, and Calvin Coolidge, who completed Harding's term but chose not to run for a full second term. Additionally, presidents such as Herbert Hoover and Jimmy Carter served only one term due to electoral defeat. Other examples include George H.W. Bush and Lyndon B. Johnson, both of whom served only one full term.