In Norse cosmology, Niflheim or Niflheimr is a location which sometimes overlaps with the notions of Niflhel and Hel. The name Niflheimr appears only in two extant sources: Gylfaginning and the much-debated Hrafnagaldr Óðins.

Norse cosmology is the account of the universe and its laws by the ancient North Germanic peoples. The topic encompasses concepts from Norse mythology, such as notations of time and space, cosmogony, personifications, anthropogeny, and eschatology. Like other aspects of Norse mythology, these concepts are primarily recorded from earlier oral sources in the Poetic Edda, a collection of poems compiled in the 13th century, and the Prose Edda, authored by Icelander Snorri Sturluson in the 13th century. Together these sources depict an image of Nine Worlds around a cosmic tree, Yggdrasil.