What cow licked the ice to reveal the first god?

The cow that licked the ice and revealed the first god was Audhumla, also spelled Auðumbla or Auðhumla.

Audhumla is a primeval cow described in Snorri Sturluson’s Prose Edda. She emerged during the earliest stage of creation, when the cold of Niflheim met the heat of Muspell. Four rivers of milk flowed from her teats, nourishing Ymir, the first primordial giant.

To feed herself, Audhumla licked salty, frost-covered stones. Over three days, she uncovered Búri: on the first day his hair, on the second his head, and on the third his whole body. Búri became the ancestor of the gods. His son Borr later fathered Odin, Vili, and Vé with the giantess Bestla.

A common mix-up is calling Audhumla the first god. She revealed Búri, who is the first god or divine ancestor in this account; Audhumla herself is the cow. Her role also links the two major ancestral lines of Norse myth: she feeds Ymir, ancestor of the giants, while uncovering Búri, progenitor of the gods.