Ichirō Ōkouchi (大河内 一楼, Ōkouchi Ichirō, born on 28 March 1968 in Sendai, Miyagi Prefecture) is a Japanese screenwriter and novelist. He is a graduate of Waseda University, School of Human Sciences.

In 2006, Ōkouchi collaborated with director Gorō Taniguchi for composing the story and script of the Sunrise original production, Code Geass: Lelouch of the Rebellion and its sequel Code Geass: Lelouch of the Rebellion R2 in 2008.