Ouroboros

The Ouroboros 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, unity, or infinity. In some representations the serpent is shown as half light and half dark, echoing symbols such as the Yin Yang, which illustrates the dual nature of all things, but more importantly, that these opposites are not in conflict… The notion of a serpent or dragon eating its own tail can be traced back to Ancient Egypt, circa 1600 BC. From ancient Egypt it passed to Phoenicia and then to the Greek philosophers, who gave it the name Ouroboros ("tail-devourer")… In Norse mythology it appears as the serpent Jörmungandr, one of the three children of Loki…

In the television series The X-Files, Dana Scully gets an ouroboros tattoo… [it is also represented in] the Sci-Fi series The Invisible Man, Breakfast of Champions by Kurt Vonnegut, The Neverending Story by Michael Ende, the James Bond novel Live and Let Die…

Image from Scribal Terror, text from Wikipedia.