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 idol, member of JO1

Fictional character

• Issei Matsukawa (松川 一静), a character from the manga and anime Haikyu!! with the position of middle blocker from Aoba Johsai High