Hideo Yokoyama (横山 秀夫, Yokoyama Hideo, born 1957) is a Japanese novelist who specializes in mystery novels.
He is also known for his career as a journalist for the Jomo Shimbun, the regional paper in Gunma.
He repeated his Kono Mystery ga Sugoi!
1 ranking in 2013 with Six Four (64).
The English edition of Six Four, translated by Jonathan Lloyd-Davies, was shortlisted for the 2016 CWA International Dagger.