Beowulf

Beowulf consists of three major battles.  You could call it a trilogy, I suppose. 
Beowulf and Grendel
Beowulf and his Mother Beowulf and Grendel's Mother
Beowulf and the Dragon

(Right.  This is not about Beowulf's mother, the daughter of Hrethel, but about Grendel's mother, evil monster mommy who is so uncivilized that she doesn't say a single word.  Pay no attention to the movie version.) 

BEOWULF AND GRENDEL
Hrothgar owns a mead hall called Heorot.  (And that's only the beginning of the alliteration.)  But then this monster named Grendel starts invading Heorot.  He carries men off to his lair.  Beowulf enters the story to kill Grendel and save Heorot.  When Grendel enters, Beowulf pretends to be drunk and asleep.  He rises and fights the monster.  He doesn't use a weapon, because that would be an unfair advantage.  It would have been a waste of time to use a sword anyway, because Grendel can't be hurt by human weapons.  So Superman Beowulf tears off Grendel's arm.  The monster goes to die in his swamp. 

BEOWULF AND GRENDEL'S MOTHER
But wait!  There's more!  Grendel's mother is mad about her son's death.  (Perhaps that's understandable, as it's her son.  Perhaps not, because he was so ugly.  Perhaps, because she's so much uglier that she thought he was beautiful.  Unfortunately, if this is so, she doesn't have a revelation like Ophelia does:  "I was the more deceived!")  Anyhow, it turns out that Beowulf has to go Grendel's-mother-fishing in the lake.  He fights her underwater.  His sword doesn't work on Grendel's mother (Beowulf, you really need to fire whoever makes your weapons), so he grabs a giant sword that Grendel's mother had in her armory.  (She'd probably eaten its owner.)  He chops off her head.  Then he finds dead Grendel and chops off his head.  He resurfaces after who knows how long (wow, he must have taken a page or two out of Obi-Wan and Qui-Gonn's book) with the proof that the monsters are dead. 

BEOWULF AND THE DRAGON
Beowulf is now King of the Geats.  (Yeats.  Yayats.  Whatever.)  A slave steals a cup from a dragon.  The dragon is (understandably) angry, and starts burning towns down and having a major temper tantrum.  (These dragons . . . they're so touchy.  Look at Smaug!  He - oh.  Ohhh.  I see the connection . . . Tolkien took inspiration from Beowulf and . . . ohhh.  Let me quote Grace - "That's so awesome!")  So Beowulf and his buddies go take an expedition to take out the dragon.  Beowulf goes down to fight it alone (at his request) and starts getting pwned.  Wiglaf (Weelaf.  Wee-loff.  Yeah, that.) is the only one who goes to help him.  Beowulf's neck gets chomped and Wiglaf stabs the dragon.  Beowulf takes that opportunity to stab the dragon, but then he dies from the wounds.  Wiglaf gets the dragon's treasure and succeeds Beowulf.