Orii Hyōjirō (折居 彪二郎) (15 July 1883 – 27 April 1970) was a Japanese specimen collector of birds and mammals.

[2][4]: 239  His career as a specimen collector took off in 1906, when he provided his services first to Malcolm Playfair Anderson, then to Alan Owston.

[4]: 239 Orii left a large number of collection diaries — an important resource for ornithologists and mammalogists — which also include lively accounts of his expeditions, such as when, having spotted a rare bird on a list of specimens obtained by the Whitney South Sea Expedition ship at the village office on Pohnpei, he promptly collected and shipped a specimen back to Tokyo, where Takatsukasa Nobusuke and Yamashina Yoshimaro published the long-billed white-eye (Rukia longirostra; protonym: Cynnirorhyncha longirostra) as a new genus and species a few weeks before Ernst Mayr published the same bird as Rhamphozosterops sanfordi.

[3][7][8]: 34  The collection diaries are compiled in a somewhat idiosyncratic fashion, interspersed with English and Chinese, and with names sometimes in hiragana, sometimes katakana; in 2013, they were published in a modern Japanese translation.

[5] The seven mammal[2] and ten bird[2] taxa named in honour of Orii Hyōjirō include:[9][10]