Guy O. Fort (January 1, 1879 – November 11, 1942) was a brigadier general in the Philippine Army under the control of the United States Army Forces in the Far East. Fort led the 81st Division (Philippines) during the initial Battle of the Philippines and the Japanese invasion of Malabang. After fighting a last-ditch stand, Fort was ordered by his higher command to surrender and be taken prisoner by Japanese forces. His captors demanded Fort help persuade his former soldiers engaged in guerrilla warfare to stop resisting the occupation. Fort refused and was executed by firing squad. Fort is the only American-born general officer to be executed by enemy forces.

Guy Osborne Fort was born in 1879 to Jacob Marvin Fort and Lena Fulkerson in Kellerville, Michigan, in an area now known as Traverse City. The family later moved to Gloversville, New York, where Fort enlisted in the U.S. Army in 1899.

Fort settled in the Philippines with his first wife, Marguerite Eugine Fort, who died in 1927 shortly after giving birth to their second son. He later married again, with his second wife Mary Angeles Adams dying at the start of World War II. His great-granddaughter was Filipina child actress, singer and model Julie Vega.

Fort regularly wrote home to family in Gloversville, and during the 1930s said he considered retiring and returning to the United States. However, he lacked a copy of his birth certificate and was unsure if he'd be allowed back, or if he could find a job during the Great Depression. His last letter home was in April 1939.

Fort served for three years in the 4th U.S. Cavalry in the Philippines before being discharged in 1902. Two years later he was commissioned as a 3rd Lieutenant in the Philippine Constabulary, a gendarmerie-style police force under American control. As a member of the constabulary, he helped suppress the Moro Rebellion.

Aside from a stint as a plantation manager from 1917 to 1922, Fort remained with the constabulary until World War II, advancing to the rank of Colonel. Stationed mainly in Mindanao, Fort was noted for both studying and observing the rituals and customs of the people he served among and for convincing outlaw bands to lay down their arms. In particular, Fort was known among the Americans as an expert on the Moro people. While in the constabulary, he also served briefly as the interim governor of the province of Agusan.

In November 1941, facing the pending Japanese invasion of the Philippines, the constabulary became part of the Philippine Army under the control of the United States Army Forces in the Far East. That month Fort was sent to Bohol to take command of the 81st Division (Philippines). On December 20, 1941, Fort was promoted to brigadier general.

Fort took his division to Lanao province in Mindanao where he organized and outfitted several battalions of Moro soldiers and planned a defense in depth for his sector. Foreseeing defeat, he also prepared his division to wage guerrilla warfare against the Japanese.