Agamemnon had two daughter's, one of whom was named Electra. Iphigenia commonly regarded as Agamemnon's daughter was actually the daughter of Theseus and Helen.
Agamemnon had two daughters with his wife Clytemnestra. They were Electra and Iphigenia. Iphigenia was sacrificed to the Gods during the Trojan war, though it is said that Artemis put a hart in her...
They have 2 daughters.
Electra-who convinced Orestes to murder Clytemnestra.
Iphigeneia- the girl who was to be sacrificed at the beginning of the Trojan War.