(by pio dal cin) The origin of fear for the number 13 comes from Nordic mythology.
The son of Odino, Balder, god of peace and light went to a banquet in the Valhalla.
Loki the god of hatred was not invited and was the 13th guest. He then convinced Hoder, the blind god of darkness to kill Balder with an arrow.
Later in times, Philip the Macedonian king added his statue to the twelve gods that were already in a procession. He was murdered shortly after that.
The Cabalah defined the number 13 number of "evil".
During the last supper there were 13 guests, among them Giudas. He was the first one to leave the table and ended up hanging himself.
Another superstion claims that if 13 people are eating together the first one to leave the table will die before the end of the year.
The number 13 becomes lucky if worn like a necklage made of gold or other material.