Kōyō, Koyo or Kouyou (written: 光洋, 光陽, 紅葉, 紅陽, 晃洋, 浩陽 or 昂洋) is a masculine Japanese given name. Notable people with the name include:

• Kōyō Aoyagi (青柳 晃洋, born 1993), Japanese baseball player
• Kōyō Ishikawa (石川 光陽, 1904–1989), Japanese photographer
• Kōyō Kawanishi (川西 浩陽, born 1959), Japanese astronomer
• Musashimaru Kōyō (武蔵丸 光洋, born 1971), American sumo wrestler
• Kōyō Okada (岡田 紅陽, 1895–1972), Japanese photographer
• Ozaki Kōyō (尾崎 紅葉, 1868–1903), Japanese writer
• Koyo Sato (佐藤 昂洋, born 1996), Japanese footballer