Chrysothemis

So Agamemnon and Clytemnestra have, depending on the version, three or four children.

They have Iphigenia, Orestes, Electra, and Chrysothemis, who isn't ever relevant.

So

sometimes there's a Chrysothemis and sometimes there isn't.

So, yeah, so they have these three children and each of them play a very important role.

Obviously, Iphigenia is killed before all of these events, so she's kind of the impetus behind them.