John Guest (7 March 1822 – 12 January 1879) was a commodore of the United States Navy, whose active-duty career lasted from the late 1830s through the Civil War.
He was appointed midshipman 16 December 1837, served in the frigate Congress during the Mexican–American War, and protected foreign residents from Chinese Imperial forces at Shanghai in April 1854.
During the Civil War, he held several sea commands and participated in actions along the Gulf Coast.
He commanded Owasco and Sangamon, passing the forts for the capture of New Orleans and engaging Confederate batteries in the siege of Vicksburg.
He was promoted to commodore in 1873, and at the time of his death was commandant of the Portsmouth Navy Yard in Kittery, Maine.