Issei or Issey is a masculine Japanese given name. Notable people with the name include:
- Issei Endō (遠藤 一星, born 1989), Japanese baseball player
- Issei Futamata (二又 一成, born 1955), Japanese actor, voice actor and narrator
- Issei Kato (加藤 壱盛, born May 28, 2003), Japanese association football player
- Issei Kitagawa (北川 一成, born 1942), Japanese politician
- Issei Koga (古賀 一成, born 1947), Japanese politician
- Issei Nishikawa (西川 一誠, born 1945), Japanese politician
- Issey Miyake (三宅 一生, 1938–2022), Japanese fashion designer
- Issei Miyazaki (宮崎 一成, born 1971), Japanese voice actor
- Issei Noro (野呂 一生, born 1957), Japanese jazz fusion guitarist
- Issey Ogata (イッセー尾形, born 1952), Japanese actor and comedian
- Issei Otake (大竹 壱青, born 1995), Japanese volleyball player
- Issei Sagawa (佐川 一政, 1949–2022), Japanese criminal
- Issei Suda (須田 一政, 1940–2019), Japanese photographer
- Issei Tajima (田島 一成, born 1940), Japanese politician
- Issei Takazaki (髙﨑 一生, born 1987), Japanese shogi player
- Issei Tanaka (田仲 一成), Japanese writer
- Issei Yamamoto (山本 一清, 1889–1959), Japanese astronomer
- Issei Mamehara (豆原 一成, born 2002), Japanese singer and actor, member of JO1
- Issei Hyodo (兵藤一誠), a character from the light novel series High School DxD
- Issei Matsukawa (松川 一静), a character from the manga and anime Haikyu!! with the position of middle blocker from Aoba Johsai High