Baron Yamashita Gentarō (山下 源太郎, 30 July 1863 – 18 February 1931) was an admiral in the early Imperial Japanese Navy.

His midshipman service was aboard the ironclad warship Ryūjō during its long-distance navigational training voyage to Wellington, Valparaíso, Callao and Honolulu in 1886.

After his return to Japan, he was assigned to a number of ships in the early navy as gunnery officer, including the ironclad Fusō, gunboat Atago (1889), corvettes Hiei (1891), Kaimon (1892) and Musashi (1893).

In July 1900, Yamashita was assigned command of Japanese marines during the Boxer Rebellion at Tientsin[1] and, after performing special duty in Hong Kong and Chefoo, he was promoted to captain in 1903.

Yamashita was promoted to rear admiral in 1908 and subsequently served as chief-of-staff of the Combined Fleet for October to December, when he was assigned to command the Sasebo Naval District.

In March 1909 he returned to the Navy General Staff as chief of the First Bureau (Operations) and in December of the same year became commandant of the Naval Academy.