An epic is a long, often book-length, narrative in verse form that retells the heroic journey of a single person, or group of persons. Elements that typically distinguish epics include superhuman deeds, fabulous adventures, highly stylized language, and a blending of lyrical and dramatic traditions.

Many of the world's oldest written narratives are in epic form, including the Babylonian Gilgamesh, the Sanskrit Mahâbhârata, Homer’s Iliad and Odyssey, and Virgil’s Aeneid. Both of Homer's epics are composed in dactylic hexameter, which became the standard for Greek and Latin oral poetry. Homeric verse is characterized by the use of extended similes and formulaic phrases, such as epithets, to fill out the verse form. Greek and Latin epics frequently open with an invocation to the muse, as is shown in the opening lines of the Odyssey:

SPEAK, MEMORY--
Of the cunning hero,
The wanderer, blown off course time and again
After he plundered Troy's sacred heights.

Speak
Of all the cities he saw, the minds he grasped,
The suffering deep in his heart at sea
As he struggled to survive and bring his men home
But could not save them, hard as he tried--
The fools--destroyed by their own recklessness
When they ate the oxen of Hyperion the Sun,
And that god snuffed out their day of return.

Over time, the epic has evolved to fit changing languages, traditions, and beliefs. Poets such as Lord Byron and Alexander Pope used the epic for comic effect in Don Juan and The Rape of the Lock. Other epics of note include Beowulf, Edmund Spenser’s The Faerie Queene, Dante's Divine Comedy, and John Milton’s Paradise Lost. The epic has also been used to formalize mythological traditions in many cultures, such as the Norse mythology in Edda and Germanic mythology in Nibelungenlied, and more recently, the Finnish mythology of Elias Lönnrot’s Kalevala.

In the twentieth-century, poets expanded the epic genre further with a renewed interest in the long poems. The Cantos by Ezra Pound, Maximus by Charles Olson, The Battlefield Where the Moon Says I Love You by Frank Stanford, and Paterson by William Carlos Williams, while not technically epics, push and pull at the boundaries of the genre, re-envisioning the epic through the lens of modernism.