This stylised symbol of three interlocking horns is most associated with the Norse God Odin. Three is an important number in Norse mythology and drinking horns figure heavily in many stories of Odin, particularly his quest for the magical mead of poetry sometimes called Odhroerir (although this can also refer to one of the Horns) created from the blood of Kvasir, another Norse God who had been murdered by dwarves. Odin hoped to gain Kvasir's wisdom by drinking this magic mead.
The motif is also often known as the Horn Triskelion. A triskele (from the Greek 'three-legged) is a symbol of threefold symmetry.)