Hideyo Amamoto (天本 英世, Amamoto Hideyo; January 2, 1926 – March 23, 2003) was a Japanese actor. He is best known for portraying Dr. Shinigami in the original Kamen Rider series as well as many other characters in tokusatsu films such as the Godzilla series. Amamoto also used the pseudonym of Eisei Amamoto for most of his career, Eisei being a misreading of the kanji in his real name, Hideyo. He died on March 23, 2003, of complications from pneumonia at 77.
Source: “Hideyo Amamoto”, English Wikipedia (CC BY-SA 4.0), excerpt