First off I want to say what epic prose and poetry is because there seems to be a lot of misconceptions with it, it's not just a long poem, its not the Lord of the Rings, its not the Rime of the Ancient Mariner or even the Raven, it's a piece of literature that embodies the the culture of a people and usually has to do with a hero going on a long epic trip to far away lands. Epic prose and poetry have existed since the dawn of time, they are our oldest literature and part of our cultural heritage, while they may not be a very popular form of writing much anymore, people still love them to this day and hopefully the style will return to its full grandeur someday.
http://www.ranker.com/list/the-greatest-epic-poems-and/zachthemusicmage,
Idylls of the King
The Divine Comedy
The Poetic Edda
The Nibelungenlied
Ovid's Metamorphoses
The Argonautica
Morte D'Arthur
The Prose Edda
Kumārasambhava of Kālidāsa (cantos I-V)
The Legend of Sigurd and Gudrún