Ryōtarō Okiayu is a Japanese actor and voice actor born on November 17, 1969, in Kitakyushu, Fukuoka. He is affiliated with the talent management firm Aoni Production and has been active in the industry since 1989. Okiayu decided to pursue a career as a voice actor during his first year of high school and later trained at the Aoni Juku Osaka school before moving to Tokyo.

He has built a prolific career with numerous major roles across anime series, OVAs, and films. Among his most notable and long-running parts is Kunimitsu Tezuka in The Prince of Tennis series, a role he has played from 2001 through to The Prince of Tennis II: U-17 World Cup Semifinal. In the 2022 anime series Ya Boy Kongming!, he voiced the lead character of Zhuge Kongming, the ancient Chinese strategist reincarnated in modern-day Shibuya. He also reprised this role for the 2024 anime film Ya Boy Kongming! Road to Summer Sonia. In the 2025 anime television series adaptation of Kowloon Generic Romance, he voices the character Miyuki Hebinuma, the president of a pharmaceutical company.

Beyond the roles specified, Okiayu's extensive filmography includes Byakuya Kuchiki in Bleach, Treize Khushrenada in Mobile Suit Gundam Wing, Hisashi Mitsui in Slam Dunk, Dark in D.N.Angel, Shigure Sohma in the 2001 Fruits Basket series, and Andrew Waltfeld in Mobile Suit Gundam SEED. He has also voiced Scar in Fullmetal Alchemist, Akio Furukawa in the Clannad series, and characters in One Piece.

Throughout his career, Okiayu has been involved in recurring collaborations, notably with the anime studio Aoni Production, his long-time agency. His range as a performer is also demonstrated by his work as a singer and as a member of the Entertainment Music Unit from 1995 to 2000. In recognition of his contributions to the industry, he was a recipient of the Best Supporting Actor Award at the 17th Seiyu Awards in 2023.