The Greek triskelion is an ancient symbol. Its name comes from the Greek word Triskeles meaning three legs. It dates back to the Neolithic era and is found on the entrance of Newgrange, Ireland. It has been used in the Celtic culture since 500 BC. It is also an ancient symbol of Sicily. This symbol dates back to when Sicily was a colony of Greece. It depicts the head of the Gorgon with snakes for hair from which radiate three legs bent at the knee.
The Greek triskelion is three interwoven spirals. It can be depicted as spirals or human legs.
One meaning attributed to the Greek triskelion is movement as the spirals represent motion. Another meaning involves groups of three. For instance, the three spirals could represent spirit/mind/body, Father/Son/Holy Ghost, Power/Intellect/Love, etc.
In modern times the Greek triskelion is seen on the seal of the United States Department of Transportation. It is also used by the Irish Air Corps. The flag of Sicily features a triskelion. It has been used in television series such as Star Trek, Merlin, Teen Wolf, and Agents of S.H.I.E.L.D.