Kōji Ochiai is a Japanese actor and voice actor born in Tokyo, Japan, with a birth date of February 4. He has been active in the entertainment industry since 1990. His career spans a wide range of roles in television animation, original net animations, theatrical films, tokusatsu productions, video games, and dubbing for foreign films and series.

Ochiai is perhaps best known for his portrayal of Tetsu Trudge (also known as Tetsu Ushio) in the long-running Yu-Gi-Oh! 5D's series. Another significant role in his career is voicing Celestino Cialdini, the former coach of the main character, in the popular figure skating anime Yuri on Ice. He is also recognized as the Japanese voice of Reuben, the sandwich-loving experiment from the Lilo & Stitch franchise, appearing in various Stitch! television series, including Stitch!, Stitch!: Itazura Alien no Daibōken, and Stitch to Suna no Wakusei. In the world of Transformers, Ochiai provides the Japanese voice for Wheelie, a role he has performed in several films, including Transformers: Revenge of the Fallen, Transformers: Dark of the Moon, and Transformers: The Last Knight.

His extensive voice filmography includes many other notable anime roles. He played Joe Gibson in the baseball series Major and Joe Gibson Jr. in Major: World Series. He voiced Minotauros in Blue Dragon, Shirō Magi in both Psychic Squad and Unlimited Psychic Squad, and Bill Clark in the second season of Ron Kamonohashi's Forbidden Deductions. Ochiai has also contributed to One Piece as Dr. Honner, Naruto: Shippuden as Iggy, Eyeshield 21 as Natsuhiko Taki and Homer Fitzgerald, and Carole & Tuesday as Benito. He voiced the character Itou in The Journey Home and Ji Dabao in the Chinese animated series Scissor Seven.

Beyond anime, Ochiai has extensive credits in video games, including roles in the Yu-Gi-Oh! series, Final Fantasy XV, Kingdom Hearts III, Yakuza: Like A Dragon, and Resident Evil 7: Biohazard. In live-action dubbing, he has lent his voice to numerous international films and television series, providing the Japanese dub for actors such as Paul Rudd, Don Cheadle, Sacha Baron Cohen, Chris Pratt, and Steve Zahn, among many others.