Beowulf
In "Annie Hall" Woody Allen's character tells Diane Keaton's character not to take any course where you have to read Beowulf and, no doubt, legions of students probably agree. I liked Beowulf, although I will admit reading the epic poem written somewhere between the 8th and 11th centuries is not easy--if you read the Old English version. The 1999 award-winning translation by Seamus Heaney is considered the best. Of course, now you can see the new movie rendition of Beowulf--I don't recall anyone like Angelina Jolie in the poem.
For a completely different experience try John Gardner's Grendel. This is the Beowulf tale turned upside down--told from the monster's point of view. Described as 'heartbreaking" and "beautiful"--Grendel is a great book.