Machiko Soga was a Japanese actress and voice actress born on March 18, 1938, in Hachioji, Tokyo. Her career in entertainment began after she was discovered following a stage performance, leading to her debut in the NHK radio drama Chorinmura to Kurumi no Ki in 1961. She initially trained in jazz dance, which helped her secure early roles in radio and voice acting.

Soga's first major anime role was as the voice of the titular character, the lovable ghost Q-Taro, in the original 1965 black-and-white television series Obake no Q-Taro, a performance that brought her initial fame. She continued to build her voice acting portfolio throughout the 1960s, notably providing the voice of Cyborg 007, also known as Great Britain, in the 1968 Cyborg 009 anime series and its accompanying film. Her other anime voice roles from this period included Totto in the series Kabatotto, Mamezō in Microid S, and Kemeko in Hana no PyunPyun Maru.

In the anime film Maken Liner 0011: Henshin Seyo!, she voiced the character Liner. Her work also extended to dubbing foreign productions, such as providing the voice of Yasha Mousekewitz in Fievel's American Tails and Chip the Bird in The Little Engine That Could. In the 1970s, Soga began to transition into live-action tokusatsu roles while continuing voice work, such as providing the voice for the robot protagonist in the 1982 series Batten Robomaru and the sidekick Ball Boy in Seiun Kamen Machineman in 1984.

While Soga's voice acting career was substantial, she became internationally renowned for her live-action performances, particularly as villainous characters in the Super Sentai and Metal Hero series. She is perhaps best known to global audiences as Witch Bandora in Kyōryū Sentai Zyuranger, as footage from this series was adapted to create the character Rita Repulsa for Mighty Morphin Power Rangers. This role created a unique situation where she later dubbed her own Japanese lines for the Power Rangers series when it was broadcast in Japan. Her portrayal of Queen Hedrian in Denshi Sentai Denjiman and Taiyo Sentai Sun Vulcan, Queen Pandora in Jikuu Senshi Spielban, and Aracnin Morgana in Sekai Ninja Sen Jiraiya further cemented her legacy in the genre.

Her final television role was a departure from her typical villainous characters, playing the heroic Heavenly Arch Saint Magiel in the 2005 series Mahou Sentai Magiranger. In a tribute following her passing, footage of Soga as Magiel was used in Power Rangers: Mystic Force to depict a reformed version of her iconic character, Rita Repulsa. Her very last performance was providing the voice and likeness for the character Dark Galaxy Queen in the PlayStation 2 video game Space Sheriff Spirits.

Machiko Soga passed away on May 7, 2006, at the age of 68. She is remembered for her significant contributions to both anime and tokusatsu, leaving behind a prolific body of work that spanned over four decades and earned her a lasting place in the history of Japanese popular culture.