Ryōtarō Okiayu is a Japanese actor, voice actor and singer affiliated with Aoni Production. His major roles include Byakuya Kuchiki in Bleach, Treize Khushrenada in Mobile Suit Gundam Wing, Hisashi Mitsui in Slam Dunk, Meisuke Nueno in Hell Teacher Nūbē, Kunimitsu Tezuka in The Prince of Tennis, Alucard in Castlevania, Zero in Mega Man X, Yuu Matsuura in Marmalade Boy, Shigure Sohma in Fruits Basket, Dark in D.N. Angel, Toriko in Toriko and Kokushibo in Demon Slayer. As a singer, he was one of the members for Entertainment Music Unit from 1995 to 2000. He is married to voice actress Ai Maeda. His range is A～E♯ and his dialect is Osakan. His older sister is an animator.

He is the official voice-over dub for Scott Foley, Taylor Kitsch, Lin Gengxin and Stephen Fung.