Why is Friday the 13th is considered an unlucky day?

It’s a little murky, but the origin of this superstition probably goes back to the Last Supper attended by Jesus Christ and his 12 disciples the night before his crucifixion on Good Friday. The 13th person has been associated with Judas Iscariot, who betrayed Christ. Additionally, the number 13 is considered “imperfect” when compared to 12, since there are 12 months in a year, 12 days of Christmas, etc.

A connection has also been made to King Philip IV of France who arrested (and later executed) hundreds of the Knights Templar on Friday, Oct. 13, 1307.