| Osman Musayevich Kasayev | |
| Caption: | Poster card featuring Osman Kasayev |
| Native Name: | Осман Мусаевич Касаев |
| Birth Date: | 11 October 1916 |
| Birth Place: | Khurzuk aul, Karachayevsky District |
| Death Date: | 18 February 1944 |
| Death Place: | Byerazino District, Byelorussian SSR |
| Branch: | Red Army |
| Serviceyears: | 1937 – 1944 |
| Rank: | Major |
| Awards: | Hero of the Soviet Union |
Osman Musayevich Kasayev (Russian: Осман Мусаевич Касаев; 11 October 1916 – 18 February 1944) was a Karachay Major in the Soviet Army during World War II who commanded a partisan detachment after his artillery division was defeated by the Germans during Operation Barbarossa. His detachment eventually became the 121st Partisan Regiment, and under his command the unit was credited with resulting the deaths of over 1,000 German soldiers before he died of injuries from an airstrike in 1944. In 1965, on the 20th anniversary of the end of the war, he was posthumously awarded the title Hero of the Soviet Union.[1]