Ryotaro Okiayu is a Japanese voice actor, singer, and narrator affiliated with Aoni Production. He was born on November 17, 1969, in Kitakyushu, Fukuoka Prefecture, and was raised in Osaka Prefecture from the third grade of elementary school. He is a graduate of the Aoni Juku Osaka School, the training school for his agency.

Okiayu's interest in voice acting began in his first year of high school. Inspired by an environment where his father, who had worked at a movie company, would bring home anime materials, Okiayu found enjoyment in imitating character voices. After saving money and receiving support from his parents, he enrolled in the Aoni Juku training school in Osaka. He passed an internal audition for Aoni Production and moved to Tokyo to begin his career.

His first professional voice work included a radio commercial and voicing a robot at the Expo '90 site. His anime debut was as a Bodkin archer in the 1989 series Dragon Quest. His first regular role came in 1991 as Franz Heinel in Future GPX Cyber Formula, and his first starring role was in the OVA Dark Cat the same year. In 1996, he landed his first lead role in a TV anime as Meisuke Nueno in Hell Teacher Nūbē, a character he has described as a culmination of his career up to that point.

Throughout his career, Okiayu has become known for his distinctive baritone voice, often portraying charismatic, aristocratic, or intense characters. Some of his most iconic and long-running roles include Byakuya Kuchiki in Bleach, Kunimitsu Tezuka in The Prince of Tennis, and Hisashi Mitsui in Slam Dunk. He has also voiced significant characters in major franchises, such as Treize Khushrenada in Mobile Suit Gundam Wing, Shigure Sohma in the 2001 Fruits Basket series, Scar in Fullmetal Alchemist, and Dark Mousy in D.N.Angel. In the long-running series One Piece, he voices both Kaku and, from episode 881 onwards, Admiral Kizaru (Borsalino), succeeding the late Unshō Ishizuka. More recently, he has taken on roles such as Kokushibo in Demon Slayer: Kimetsu no Yaiba and Zhuge Kongming in Ya Boy Kongming!. He has also appeared in numerous other series, including Date A Live (as Isaac Ray Pelham Westcott), Digimon Ghost Game (as Airdramon), and Utawarerumono: Mask of Truth (as Raikou).

In addition to his anime work, Okiayu is active in video games, with notable roles including Zero in the Mega Man X series, Akio Furukawa in the Clannad visual novel and its anime adaptation, and Lancelot in the Fate series. He has also been involved in dubbing foreign films and dramas, providing the Japanese voice for actors such as Scott Foley, Taylor Kitsch, and Lin Gengxin.

Okiayu has also been active as a singer. He was a member of the popular voice actor unit E.M.U. (Entertainment Music Unit) from 1995 to 2000, alongside Hideo Ishikawa, Hikaru Midorikawa, Nobutoshi Canna, and Daisuke Sakaguchi. He has also participated in various music groups related to The Prince of Tennis franchise, such as Aozu and GIGS. Beyond voice acting, he has been working as a stage actor with the theater company Hero Hero Q Company since 2016.

His contributions to the industry were recognized in 2023 when he received the Best Supporting Actor Award at the 17th Seiyu Awards for his performance as Kokushibo in Demon Slayer: Kimetsu no Yaiba.