Jörmungandr or Jormungandr can refer to:
Jörmungandr, a giant sea serpent in Norse mythology Midgard Serpent (Marvel Comics), also known as Jormungand Jormungandr, a genus of fossil mosasaurs with only one member, Jormungandr walhallaensis Joermungandr, a genus of fossil tetrapods with only one member, Joermungandr bolti Jormungand (manga), a manga series