Baisao (1675 -1763) was a Japanese Buddhist monk of the Obaku school of Zen Buddhism, who became famous for traveling around Kyoto selling tea.
Baisao, "Old Tea Seller", was a name he picked up from his act of making tea in the Kyoto area. His Zen priest name was Gekkai Gensho.
Later in his life, he denounced his priesthood and adopted the layman name of Ko Yugai.
Baisao's poetry and calligraphy are considered important in the Zen history of Japan, especially in Kyoto where Baisao was well known for offering tea to passers-by in return for donations. His poetry was highly regarded by the artists of 18th century Kyoto, which was at the time more "liberal" than the capital city of Edo (modern Tokyo). Over 100 of his poems have survived.