Hiroshi Miyauchi is a Japanese actor and voice actor known primarily for his extensive work in tokusatsu productions, which are live-action special effects films and television series. Born on June 14, 1947, in Chiba Prefecture, he is a graduate of Nihon University and holds a first-degree black belt in judo. His career in entertainment began in 1968.

Miyauchi gained prominence in the early 1970s for his leading role as Shiro Kazami, the titular hero Kamen Rider V3, in the 1973 series Kamen Rider V3. He would reprise this character numerous times over the following decades, including appearances in Kamen Rider X, Kamen Rider Stronger, Kamen Rider (Skyrider), and the film Kamen Rider Super-1. In the 2011 film OOO, Den-O, All Riders: Let's Go Kamen Riders, he once again voiced the role of Shiro Kazami, also known as Kamen Rider V3. Beyond performing as the character in live-action, he also provided his voice for the role in various productions. In 2025, he voiced Kamen Rider V3 in the animated series Tojima Wants to Be a Kamen Rider.

In the Super Sentai franchise, Miyauchi is recognized for his portrayal of Akira Shinmei, who is the Aorenger, in the 1975 series Himitsu Sentai Gorenger. He also played Soukichi Banba, also known as Big One, in the 1977 series JAKQ Dengekitai. He later took on the role of Chief Councillor Naoyuki Miura in the 1995 series Chōriki Sentai Ohranger. In the anniversary film Gokaiger Goseiger Super Sentai 199 Hero Great Battle, he returned to voice his characters from Gorenger and JAKQ Dengekitai.

His other notable tokusatsu roles include Ken Hayakawa, the hero Zubat, in the 1977 series Kaiketsu Zubat, and Shunsuke Masaki in the Metal Hero series Tokkei Winspector, Tokkyuu Shirei Solbrain, and Tokusou Exceedraft. In the 2005 film Kamen Rider The First, he took on the part of Tobei Tachibana, a mentor character originally from the early Kamen Rider series.

In the field of voice acting for non-Japanese productions, Miyauchi is known for providing the Japanese dub voice of SkekSil, the Skeksis Chamberlain, in Jim Henson's fantasy film The Dark Crystal. He also performed the opening theme song for Kamen Rider V3 and insert songs for Kaiketsu Zubat and Tokkei Winspector.