Who betrayed agamemnon?

Agamemnon was betrayed by his wife, Clytemnestra. After he sacrificed their daughter, Iphigenia, to appease the gods for favorable winds to sail to Troy, Clytemnestra harbored resentment and ultimately conspired with her lover, Aegisthus. Upon Agamemnon's return from the Trojan War, she killed him in revenge for his actions and her own feelings of betrayal.