Ryūō ('dragon king') is an annual Japanese professional shogi tournament and the title of its winner. It may also refer to:
Ryūjin, the mythological sovereign of the Ryūgū-jō ("Dragon Palace") Ryūō, Shiga, a town in Gamō District, Shiga Prefecture, Japan Ryūō, Yamanashi, a former town in Nakakoma District, Yamanashi Prefecture, Japan Ryūō Station, a railway station in Kai, Yamanashi Prefecture, Japan Ryuoo Ropeway, an aerial lift in Yamanouchi, Nagano Prefecture, Japan Ryūō Noboru (born 1983), Mongolian sumo wrestler
See also The Ryuo's Work Is Never Done!, a Japanese light novel series