James, Jim, or Jimmy Barnes may refer to:

Politics

• James Barnes (Canadian politician) (1842–?), farmer, lumberman, railway contractor and political figure in New Brunswick, Canada
• James M. Barnes (politician) (1899–1958), U.S. Representative from Illinois
• James Strachey Barnes (1890–1955), British Fascist Party member and diarist
• Sir Jim Barnes (politician) (1908–1995), New Zealand politician

Sport

• James Barnes (cricketer) (1886–1963), English cricketer
• Jim Barnes (1886–1966), English professional golfer
• Jim Barnes (offensive guard), American football player
• Jim Barnes (American football, born 1959), American football player and coach
• Jim "Bad News" Barnes (1941–2002), American basketball player

The arts

• James Barnes (author) (1866–1936), American author
• James Barnes (composer) (born 1949), American composer
• James Barnes (television director) (born 1979), English television director
• Jim Barnes (writer) (born 1933), Native American writer
• Jimmy Barnes (born 1956), Scottish-Australian rock musician

Other people

• James Barnes (engineer) (1740-1819), English Canal engineer
• Sir James Barnes (civil servant), English civil servant
• James Barnes (general) (1801–1869), American railroad executive and Union Army general in the American Civil War
• James Barnes Wyngaarden (1924–2019), American medical researcher
• James William Barnes Steveni (1859–1944), British correspondent in Russia
• A. James Barnes (born 1942), American attorney, dean and professor
• James Barnes (murderer) (1962–2023), American convicted murderer, interviewed in prison by Werner Herzog
• James Stevenson Barnes, British colonel who served in the Napoleonic Wars
• James Antonio Barnes (born 1944), American serial killer

Characters

• Bucky Barnes also known as James Barnes, sidekick of Captain America and inheritor of the name

Other

• James B. Barnes House, a historic site in Cambridge, Massachusetts