Ainu or Aynu may refer to:

• Ainu people, an East Asian ethnic group of Japan and the Russian Far East
  • Ainu languages, a family of languages
    • Ainu language of Hokkaido
    • Kuril Ainu language, extinct language of the Kuril Islands
    • Sakhalin Ainu language, extinct language from the island of Sakhalin
  • Ainu music
  • Ainu cuisine
• Ainu (Middle-earth), spirit in J. R. R. Tolkien's legendarium
• Ainu (insect), a beetle in the family Tenebrionidae
• Äynu people, of Western China
  • Äynu language

• Äynu (disambiguation)
• Ainur (disambiguation)
• Aino (disambiguation)
• Aniu, character from Balto II