Epic heroes are generally the main characters in epic poems. They also typically represent their culture by embodying the values that their culture admires. For example, Odysseus is the main character in the Greek epic, "Odyssey". Odysseus was a quick thinker and clever, which Greeks at the time greatly admired. Epic heroes may also possess superhuman strength or military skill.
Epic poems are specifically a genre of poetry in the classical world. These poems are generally long, narrative poems that are concerned with a serious subject. They focus on the exploits of the epic hero and are told in elevated style of language. Finally, the success or failure of the epic hero may be responsible for the fate of the hero's people or nation.
Ancient Greek and Roman texts, such as "Odyssey" and the "Aeneid," most accurately represent epic poetry. Many critics apply the term to other works of poetry from other cultures around the world, however. "Beowulf" is often called an Anglo-Saxon epic, and "Paradise Lost" may be considered an epic of Christian culture.
To make it short it's :
An epic hero is defined as a character in an epic poem is noble and brave and it's affected by a great events or admired for his achievements.