Walder Frey

Lord of the Twins, the great river-spanning castle that gave House Frey its leverage over every army that ever needed to cross the Green Fork, Walder married eight times and fathered a small army of trueborn children, bastards, and grandchildren, most of whom he can no longer be bothered to name correctly. He earned his mocking epithet by arriving at the Trident in 283 AC only after the battle was already decided, having waited to see which side would win before committing his men — a caution the rest of Westeros's great houses have never let his family live down.

When Robb Stark broke a marriage pact made to secure Frey support for his war, wedding Jeyne Westerling instead of one of Walder's daughters, Walder nursed the insult for months while appearing to accept an apology and a substitute match. He then conspired with Tywin Lannister and Roose Bolton to slaughter Robb, his mother Catelyn, and the greater part of his bannermen at a wedding feast under his own roof in 299 AC — a massacre carried out in flagrant violation of guest right, the oldest and most sacred law of hospitality the Seven Kingdoms recognize.