Friday the 13th superstition stems from combining the unlucky number 13 (derived from the Last Supper's 13th guest, Judas, and Norse myth) with Friday, traditionally viewed as a day of misfortune or crucifixion. The combination likely originated in the late 19th or early 20th century, popularized by historical events like the 1307 Templar arrests and literary references.
Key Origins and Beliefs:
Biblical Connections: Judas Iscariot, who betrayed Jesus, was the 13th guest at the Last Supper, and Jesus was crucified on a Friday.
Norse Mythology: A banquet for 12 gods was ruined when the 13th guest, the trickster Loki, arrived, leading to the death of Balder.
Historical Event: On Friday, October 13, 1307, King Philip IV of France ordered the arrest of the Knights Templar, a significant event often cited as the origin of the curse.
Number 13: Ancient Sumerians and Romans viewed 13 as an unlucky, irregular number.
Friday: Historically regarded as an unlucky day, associated with events like the temptation of Eve and the fall of Adam.
Cultural Popularity: While roots are older, the specific combination of Friday the 13th became more recognized in the late 19th century, with early references in literature. The term for the fear of this day is paraskevidekatriaphobia.

Loki is one of my favorite mythology figures