Why they fought: The Mountain flipped out after losing a tourney battle to Ser Loras. The Hound jumped in and saved Loras' life (but wasn't fast enough to save that poor decapitated horse).
Winner: King Robert stopped the fight before either Clegane could claim victory, but The Hound impressively held his own against his brother, arguably the most feared fighter in Westeros.
Eddard vs. Jaime
Season 1, Episode 5
Why they fought: Jaime was mad Catelyn took Tyrion hostage. Eddard was mad Jaime had his men killed.
Winner: Jaime. Although the fight was cut short when a man put a spear through Eddard's leg, the Kingslayer had the upper hand throughout the contest.
Bronn vs. Ser Vardis Egan
Why they fought: Tyrion stood accused murdering Jon Arryn and attempting to kill Bran. Tyrion convinced Bronn to take up his cause in the trial by combat.
Winner: Bronn, who saved Tyrion from flying out the Moon Door. Egan fought with honor, but ended up losing — a key theme of the show.
Khal Drogo vs. Mago
Season 1, Episode 8
Why they fought: Mago challenged Drogo's rule when he allowed Daenerys to protect women from rape: "A Khal who takes orders from a foreign whore is no Khal."
Winner: Drogo, who ripped out Mago's throat with his bare hands and delivered some of his most badass lines of the series. ("The worms will crawl through your lungs!"). Sadly, the wound Mago gave Drogo would later prove fatal.
Ser Jorah Mormont vs. Qotho
Season 1, Episode 9
Why they fought: Qotho was angry about Daenerys bringing in a witch to heal Khal Drogo. Jorah was not about to let someone harm his queen.
Winner: Ser Jorah, who proved that armor comes in handy during a fight. Qotho attempted to strike a death blow, only to have his curved blade blocked by Jorah's "metal dress."
Jon Snow vs. Qhorin Halfhand
Season 2, Episode 10
Why they fought: Qhorin wanted the Wildlings to trust Jon, and believed sacrificing himself was the only way to do it.
Winner: Jon, who went on to infiltrate the Wildling camp thanks to the Qhorin's selfless move. Could Jon have killed Qhorin had it not been a fixed fight? Our money says yes.
The Hound vs. Beric Dondarrion
Season 3, Episode 5
Why they fought: The Hound stood accused of killing the butcher's boy and got a trial by combat.
Winner: The Hound, despite Beric Dondarrion playing a bit dirty and lighting his sword on fire. "Looks like the Gods likes me more than your butcher's boy," he tells Arya. As for Beric? He was brought back from the dead, so no big deal.
Brienne and Jaime vs. a Bear
Season 3, Episode 7
Why they fought: Brienne and the bear were forced to fight by the horrible Locke. Jaime heroically jumped in to the battle to help his friend, who was armed with just a wooden sword.
Winner: We'll give Jaime and Brienne credit for their quick escape, but let's face it, the bear was going to win.
Jon Snow vs. Karl Tanner
Season 4, Episode 5
Why they fought: Karl had gone crazy and taken over Craster's Keep. Jon wanted Karl and his men to die before they could give up strategic information to the Wildlings
Who won: Jon, thanks to an assist from one of Craster's wives.
Prince Oberyn Vs. The Mountain
Season 4, Episode 8
Why they fought: Oberyn volunteered to stand for Tyrion in his second trial by combat, knowing it would be his chance to avenge his sister's rape and murder.