The number that seems to be almost universally considered unlucky ancient Romans regarded it as a symbol of death, destruction, and misfortune. One of he earliest written stories about the number 13 appears in Norwegian mythology. This story tells about a feast at Valhalla to which 12 gods were invited. Loki, the gid of evil, came uninvited, raising the number to 13 . In the struggle to throw out Loki, Balder, the favorite of the gods, wan killed.