Third Person (Objective), Third Person (Limited Omniscient)
Technically speaking, Agamemnon doesn't have any narrator at all, because it's a play. Instead of hearing about what characters do, we actually see them do it. Of course, those characters also talk about themselves, in which case they act as first-person narrators, and about each other, in which case they act as either second or third person narrators. Of the narrations within the play, the most notable are those of the Chorus, when recounts Agamemnon's experiences leading up to the Trojan War from a Third Person Limited Omniscient point of view, and of Cassandra, when she recounts the crime of Atreus, from the same point of view.