Mantarō Iwao is a Japanese voice actor born on January 22, 1966, in Oita Prefecture, Japan. He is affiliated with the talent agency Hai Kyō. His professional training includes time at the Hai Kyō training school as part of the fourth generation, followed by membership in theatrical troupes such as Gekidan Bōkendan, Gekidan Tokyo Ichi Gumi, and King Monkey III. One of his personal skills is speaking the Oita dialect.

Iwao is known for his work in anime, where he has provided voices for a range of supporting characters. In the mecha genre, he voiced Grappler Gouf in the series SD Gundam Force. He also voiced the character Skywarp, known as the Sonic Instructor, in the Transformers franchise, including the 1998 series Beast Wars II: Super Lifeform Transformers and the film Beast Wars Second: Lio Convoy Kiki Ippatsu.

His other notable anime roles include Ryōsuke Morimi in Eden of the East, Sōun Miki in Kamichu!, Geoff in Emma: A Victorian Romance, Raj Puhto in Ghost in the Shell: Stand Alone Complex - Solid State Society, and a monk in the television series adaptation of Air. He also appeared as Nozomu’s father in the anime Twin Love.

In addition to traditional animation, Iwao has voiced characters in live-action productions. He guest-starred as the voice of the alien Zoinaian Baytonin in an episode of the Super Sentai series Tokusou Sentai Dekaranger. He also voiced Trinoid 13, Mukadenpanji, in another Super Sentai series, Bakuryū Sentai Abaranger. His work in dubbing foreign media includes providing the Japanese voice for Ned Leeds in the 1994 animated Spider-Man series. He has also performed voice work for Japanese dubs of live-action films, such as playing the Commander of the Special Assault Team in 20th Century Boys.

Throughout his career, Iwao has collaborated with several other voice actors on multiple projects. He has worked frequently with Takashi Nagasako on series including Kamichu!, The Melancholy of Haruhi Suzumiya (as the voice of Nozomu’s father), Black God, and the Super Sentai franchises. He has also shared credits with Kouichi Sakaguchi on Eden of the East, Darker than Black: Gaiden, and various Super Sentai series. Other frequent collaborators include Tetsu Inada, who voiced Doggie Kruger in Dekaranger, and Dai Matsumoto, who worked with Iwao on projects such as SD Gundam Force and Abaranger.