Hiroo Oikawa was a Japanese voice actor born on August 28, 1935, in the Hokkaido Prefecture of Japan. He passed away on September 25, 1995. His birth name was Hiroo Oikawa, written with the given name 広夫, though he was typically credited using the katakana rendering ヒロオ.

Oikawa's career encompassed voice acting in anime and dubbing foreign films for Japanese television. In anime, he is recognized for several roles from the late 1970s through the 1980s. He voiced Chief Engineer Kamo in the 1979 series Science Ninja Team Gatchaman Fighter. He also played the role of Chuzai in the 1981 television series Fūsen no Doratarō. Another noted anime role was Sanpei in the 1988 special Kosuke-sama, Rikimaru-sama: Konpeitō no Ryū.

His other anime voice work included roles such as Jehan (the grandfather) in the 1975 television series A Dog of Flanders, Principal Ochaka in the 1983 Time Bokan Series Itadakiman, and Professor Dekro in the 1987 feature film Royal Space Force: The Wings of Honnêamise. He also had guest roles in long-running series, appearing in episodes of Lupin III: Part II.

Beyond anime, Oikawa was active in voice-over work for Western films and series dubbed into Japanese. His dubbing credits include providing the Japanese voice for Parker, the butler, in VHS releases of the Thunderbird puppetry series and its film Thunderbird 6. He also voiced roles in television broadcasts of classic films such as Roman Holiday (as the taxi driver) and Butch Cassidy and the Sundance Kid (as the police chief). Additional dubbing work included parts in the Mr. Vampire film series and the television dramas The Twilight Zone and Street Hawk. Oikawa also appeared in live-action roles, with credits including the 1987 film The Red Spectacles and the 1995 film Minna Yatteru Ka.