Which episode of Game of Thrones is commonly called the Red Wedding episode?

The Game of Thrones episode commonly called the Red Wedding is “The Rains of Castamere.” It is the ninth and penultimate episode of season 3, and the 29th episode overall.

The episode centers on the wedding of Edmure Tully and Roslin Frey at the Twins. During the feast, Walder Frey and his allies break the rules of guest right and turn the celebration into a massacre. Robb Stark, his wife Talisa, his mother Catelyn, and many Stark bannermen are killed or betrayed.

The title comes from “The Rains of Castamere,” an in-universe Lannister song about the destruction of House Reyne. Its performance at the wedding acts as a warning that the massacre is about to begin. The episode also follows Bran Stark, Jon Snow, and Daenerys Targaryen in separate storylines.

It first aired on June 2, 2013, and became one of television's most discussed episodes. “The Red Wedding” describes the event, while “The Rains of Castamere” is the official episode title.