Friday the 13th is considered unlucky by many people (Credit: Pixabay/ CC-BY-SA-2.0)

American singer-songwriter Taylor Swift and her fans may consider 13 a lucky number. However, millions of people worldwide do not share that sentiment. Things get even worse for the superstitious when the date, as will happen this week, coincides with a Friday. Some of the anxiety surrounding Friday the 13th can be blamed on the namesake movie series. However, the day was feared long before the film's hockey-masked villain, Jason Voorhees, made his debut in 1980.