Slavic mythology is the mythological aspect of the polytheistic religion that was practised by the Slavs before Christianisation.

The religion possesses many common traits with other religions descended from the Proto-Indo-European religion.

Unlike Greek or Egyptian mythology, there are no first-hand records for the study of Slavic mythology. Despite some arguable theories (for instance, the Book of Veles), it cannot be proven that the Slavs had any sort of writing system before the arrival of Saints Cyril and Methodius to Slavic lands in 862. Therefore, all their original religious beliefs and traditions were likely passed down orally over the generations, and basically forgotten over the centuries following their rapid conversion into Christianity (which began with conversion of Bulgaria in 864 and was largely complete by the late 11th century.) Before that, sparse records of Slavic religion were mostly written by non-Slavic Christian missionaries who were uninterested in accurately portraying pagan beliefs. Archaeological remains of old Slavic cult images and shrines have been found, though little can be yielded from them without legitimate knowledge of their contexts, other than confirming existing historical records. Fragments of old mythological beliefs and pagan festivals survive up to this day in folk customs, songs, and stories of all the Slavic nations.