Ōi

Ōi may refer to:

Japanese geography

 * Ōi, Fukui
 * Ōi, Kanagawa
 * Ōi, Saitama
 * Ōi District, Fukui
 * Ōi River, Shizuoka Prefecture
 * Ōi River (Kyoto Prefecture), part of the Katsura River

People with the surname

 * Katsushika Ōi (c. 1800 – 1866), Japanese ukiyo-e artist
 * Naoyuki Ōi (大井 直幸), Japanese pool player

Other uses

 * Grey-faced petrel, also known by its Māori name Ōi
 * Ōi (shogi), one of the eight titles of Japanese professional shogi (board game) tournament
 * Ōi Dam, Gifu Prefecture, Japan
 * Japanese cruiser Ōi, a former cruiser in the Imperial Japanese Navy