It could be considered many things such as Fantasy, Greek Mythology, but if memory serves me correct it is simply called an "Epic" because it centers around Heroes and Monsters.
The Odyssey is an example of a Greek epic poem. It is composed of 24 songs, attributed to the Greek poet Homer. It is believed that it was composed in the 8th century BC. C. in the settlements that had Greece on the west coast of Asia Minor (current Asian Turkey).
