Tokugawa Ieyasu
Tokugawa Ieyasu was the great daimyo who unified Japan and became shogun in 1603. He was the greatest patron of Go of all time. Tokugawa supported the establishment of the Go houses (Honinbo, Yasui, Inoue, and Hayashi) and created the office of godokoro in the government. He began a system of government support for Go players in Japan, and he established the formal castle games. His policies were continued by his heirs until the Meiji Restoration, in 1868. -- Bob McGuigan
Ieyasu, as well as his contempories, Oda Nobunaga and Toyotomi Hideyoshi, were all pretty strong go players -about a 5 stone handicap to pros, according to 'The World of Go', by Nakayama Noriyuki - kokiri
See also