Alcyoneus, Halcyoneus or Alkyoneus (from ) may refer to:
Alcyoneus (mythology), several figures in Greek mythology Alcyoneus, a character in Rick Riordan's The Heroes of Olympus novels; see list Hylaeus alcyoneus, a bee species endemic to Australia Halcyoneus or Alcyoneus, the son of Antigonus II Gonatas Alcyoneus (galaxy), an unusually large radio galaxy