|There is no clear origin for why Friday the 13th is considered unlucky. One of the first connections of the number 13 with bad luck comes from Norse mythology. When 12 gods attended a feast in Valhalla, the mischief-maker Loki party-crashed as the 13th guest and arranged that the blind god Höðr inadvertently killed Baldur, the god of joy and innocence, with a projectile made out of mistletoe. In Scandinavia it has long been considered bad luck to have 13 people at a dinner
party. This belief has been strengthened in the Christian world by another dinner party ending rather badly, the Last Supper.