First Lieutenant Jack Llewellyn Knight (May 29, 1917 – February 2, 1945) was an American National Guard officer who was killed in action during World War II. He was awarded the United States' highest military decoration for valor, the Medal of Honor, posthumously. He was inducted to the Texas Military Hall of Honor in 1980, awarded the Texas Legislative Medal of Honor posthumously on 31 May 1999.

First Lieutenant Knight was born in Garner, Texas. He graduated from Weatherford Junior College, in Weatherford, Texas, in 1938, and joined the Texas National Guard on 18 November 1940 along with his brother Curtis. Jack graduated from Cavalry OCS at Fort Riley, Kansas. He served as Commander of F Troop (His brother Curtis was the First Sergeant) in the 124th Cavalry Regiment, Mars Task Force.

On 2 February 1945 near Loi Kang, Burma, Knight single-handedly destroyed two Japanese pillboxes. Despite being wounded, he led his rifle platoon in an attack on other enemy positions but was again wounded, this time fatally. For his heroic actions, he was awarded the Medal of Honor posthumously four months later, on 25 June 1945. His regimental commander, Colonel William F. Osborne, veteran of Bataan and Merrill's Marauders, said of Jack Knight, "In more than four years of combat, I have seen many officers fight and die, but LT Knight's action in leading his troop to its objective against strong enemy concentrations is to me the finest example of courage, valor, and leadership of any officer I have ever commanded.

Knight, aged 27 at his death, was buried at the Holders Chapel Cemetery in Cool, Texas.

His military awards and decoration include the Medal of Honor, Combat Infantryman Badge , Bronze Star Medal, Purple Heart, Army Good Conduct Medal, American Defense Service Medal, American Campaign Medal.