| Sentarō Ōmori 大森 仙太郎 | |
| Native Name: | 大森 仙太郎 |
| Native Name Lang: | jpn |
| Birth Date: | 1892 10, df=y |
| Death Date: | [1] |
| Birth Place: | Kumamoto Prefecture, Japan |
| Serviceyears: | 1913–1945 |
| Rank: | 30px Vice Admiral |
| Battles: | |
| Alma Mater: | Imperial Japanese Naval Academy |
, was an admiral in the Imperial Japanese Navy during World War II.
Ōmori was born in Kumamoto prefecture and graduated from the 41st class of the Imperial Japanese Naval Academy in 1913. He was ranked 16th out of 118 cadets. He served his midshipman duty aboard the cruiser, battleships and, and was commissioned as an ensign in 1914. He subsequently served on the battleship and destroyer .
Ōmori returned to school, and became a torpedo expert. He served as lieutenant on the destroyers and and the battleship before being given his first command on 1 December 1923: the destroyer .
Through the 1920 and 1930s, Ōmori subsequently commanded the destroyers, and, seaplane tender Kawakami Maru, and finally the battleship from 1939–1940, while steadily increasing in rank and returning at regular intervals to torpedo school to remain expert on the latest developments in torpedo technology and tactics. He was promoted to rear admiral on 15 November 1940.
At the start of World War II, Ōmori was in command of Destroyer Squadron 1 (DesRon1), which accompanied the main strike force during the attack on Pearl Harbor. It also participated in the Indian Ocean Raid of early 1942. During the Battle of Midway, DesRon1 directed the occupation of Attu Island in the Battle of the Aleutian Islands. Omori was given command of Cruiser Division 5 (CruDiv5). Assigned to the Solomon Islands, he was ordered to attack American transports off Bougainville Island in early November 1943. In the resultant Battle of Empress Augusta Bay of 1–2 November 1943, the Japanese forces (heavy cruisers and, light cruisers and, and destroyers,,,,, and) suffered a decisive defeat. Ōmori and his heavy cruisers narrowly escaped damage in an air raid at Rabaul, New Britain the following day, and retreated to the main Japanese base at Truk, Caroline Islands. Ōmori was relieved of his command for having withdrawn at Empress Augusta Bay against an inferior force and was sent back to Japan.
Ōmori became Commandant of the Torpedo School, and was promoted to vice admiral on 1 July 1944. He was director of the Special Attack Division from 13 September 1944–10 August 1945, supervising work with the Kaiten human-guided torpedoes. At the very end of World War II, he was appointed Commander in Chief of the IJN 7th Fleet.
Ōmori died on 24 December 1974.