Hideki Kawaguchi is a Japanese former child actor known for his work in tokusatsu (live-action special effects) television dramas and films from the late 1960s through the mid-1970s. While often associated with hero series that share a fan base with anime, his on-screen performances are in live-action productions.

Kawaguchi was born in 1961 in Japan. He began his career as a child actor, and one of his earliest roles was in the 1967 series "光速超能人" (Kōsoku Esupā). He gained recognition for his portrayal of坂田次郎 (Sakata Jiro), the younger brother of a supporting character, in the series "帰ってきたウルトラマン" (Return of Ultraman), which aired from 1971 to 1972. He reprised this role in several related films.

Kawaguchi is also known for playing the character Shigeru Tama in the 1973 series "仮面ライダーV3" (Kamen Rider V3). Shigeru Tama is the younger brother of Junko Tama, a friend of the main protagonist, Shiro Kazami. He appeared in the television series as well as the theatrical feature "仮面ライダーV3対デストロン怪人" (Kamen Rider V3 vs. Destron Mutants).

Other notable tokusatsu roles during this period include appearances in "ウルトラマンA" (Ultraman Ace) and "人造人間キカイダー" (Android Kikaider). His career as a performer concluded in the latter half of the 1970s.

No reliable or verifiable information is available about his life after retiring from acting, personal details, or any work as a voice actor in anime productions. Information regarding his activities following his childhood career is inconclusive.