Hellanicus or Hellanikos (Ancient Greek: Ἑλλάνικος) may refer to:

• Hellanicus of Lesbos (5th century BC), Greek logographer and historian
• Hellanicus (grammarian) [it] (3rd century BC), Greek grammarian; see Chorizontes
• Hellanicus (mythology), one of the suitors of Penelope
• Hellanicus, supposed author of the Hieronyman Theogony