Ruan Xiaowu (阮小五), also known as Ruan the 5th is a character in the Water Margin. As part of the trio the Ruan brothers, Ruan sat on the council of the 36 Heavenly Spirits in the Liangshan contingent, which peaked at 108 members.
Ruan Xiaowu had eyes like bells, and arms like iron staffs. Although he wore a smile on his face, a murderous impression could be detected. He had a tattoo of a leopard on his chest, and was nicknamed the 'Short-lived second brother (短命二郎)'.