Prince Yakov Gerasimovich Bagratuni (Armenian: Հակոբ Բագրատունի; August 25, 1879 - December 23, 1943) was a major general in the Russian Empire and the First Republic of Armenia during World War I, and later became Armenia's ambassador to the United Kingdom. His lineage comes from the Bagratuni dynasty, which ruled Armenia in the Middle Ages. Bagratuni served as an officer in Warsaw and successfully completed an important intelligence mission in Persia. In 1904, he was promoted to lieutenant and entered the Academy of the General Staff, but in early 1905, his studies were interrupted due to participation in the Russo-Japanese War, where he commanded a company in the 19th East Siberian Regiment. For his combat merits, he was awarded the Order of Saint Anna 4th class and the Order of Saint Stanislaus 3rd class with swords.

In the Turkestan Military District, Bagratuni carried out secret missions in Mongolia, Tibet, Korea, Afghanistan, and Central Asia, including Bukhara, Kashgar, Kermish, Kushka, and Merv. He uncovered a conspiracy of pan-Turkist emissaries in Tashkent and other cities of Turkestan, for which he was awarded the Order of Saint Anna 3rd class. During World War I, he received multiple awards and on November 22, 1916, became the commander of the 8th Turkestan Infantry Regiment.

Bagratuni supported the February Revolution and became an associate of War Minister Kerensky, whose sister was his wife. In 1917, he was promoted to major general and unsuccessfully opposed the Kornilov coup and the Bolshevik revolution. After a brief arrest by the Bolsheviks, he returned to the Caucasus. In the autumn of 1918, he was appointed Minister of War of the Central Caspian Dictatorship. After the return of British troops to Baku, he rejoined the Armenian National Council. In 1919, he participated in the Paris Peace Conference as an advisor to the Armenian delegation. In 1920, Bagratuni became the ambassador of the Republic of Armenia in the United Kingdom, where he remained in exile.

Bagratuni passed away on December 23, 1943, in the town of Lostwithiel, Cornwall. After a memorial service at the Armenian church in London on January 3, 1944, he was buried at Brompton Cemetery.

Yakov Gerasimovich's son, Dr. Lev Bagratuni (July 7, 1920 - November 18, 1964), was a senior lecturer in the Department of Clinical Biochemistry at Oxford and conducted numerous studies in the field of rheumatism. One of the rheumatic diseases he studied was named in his honor.

Also buried next to Yakov Gerasimovich Bagratuni is his son George Bargatuni (1914, 1996).