Det var en gång

Det var en gång is the Norwegian language and Swedish language equivalence of the expression once upon a time.

Det var en gång may refer to:
 * Det var en gang (film), 1994 Norwegian animated film directed by Ketil Jakobsen
 * "Det var en gang" song by Mabelin during Melodi Grand Prix Junior 2002 competition
 * "Det var en gång en fågel", song by Laser Inc on their album Roger That!
 * "Ett gammalt fult och elakt troll det var en gång", also known in short title "Det var en gång", traditional Swedish children's song