In Goidelic mythology, Boann ("she of the white cattle") was the wife of Necthan or Elcmar. Her lover was Dagda, by whom she was the mother of Aengus. In order to hide their affair, Dagda made the sun stand still for nine months; therefore, Aengus was conceived, gestated and born in one day.

She was associated with a sacred white cow.

Alternative name: Boand