Paraskavedekatriaphobia is the fear of Friday the 13th

The fear of Friday the 13th is named paraskevidekatriaphobia. Paraskavedekatriaphobia is a concatenation of the Greek words Paraskeví (meaning “Friday”), and dekatreís (meaning “thirteen”) attached to phobía (from phóbos, meaning “fear”).
Another word for the fear of Friday the 13th is friggatriskaidekaphobia (frigga meaning “Friday” and triskaidekaphobia meaning fear of the number thirteen).

Source: Wikipedia