The Ouroboros (also spelled Oroborus, Uroboros or Uroborus) is an ancient symbol depicting a serpent or dragon swallowing its own tail and forming a circle. It has been used to represent many things over the ages, but it most generally symbolizes ideas of cyclicality and primordial unity. The ouroboros has been important in religious and mythological symbolism, but has also been frequently used in alchemical illustrations. In the last century, it has been interpreted by psychologists such as Carl Jung as having an archetypal significance to the human psyche.

The name ouroboros (or, in Latinized form, uroborus) is Greek οὐροβóρος, "tail-devourer". The depiction of the serpent is believed to have been inspired by the Milky Way, as some ancient texts refer to a serpent of light residing in the heavens. ^{[citation needed]}