Castor and Pollux.

Castor (Κάστωρ) and Pollux (Πολυδεύκης) were twin brothers in Greek mythology. Also, they were called Dioscuri (Διόσκοροι, Διόσκουροι).

Leda (Λήδα) was Castor's and Pollux's mother. Tyndareus (Τυνδάρεος) (Tundáreōs) was Castor's father. Zeus was Pollux's father.

Timandra (Τιμάνδρα), Clytemnestra (Κλυταιμνήστρα) (Klutaimnḗstra), Helen of Sparta, Philonoe (Φιλονόη), and Phoebe (Φοίβη) (Phoíbē) were Dioscuri siblings.

These brothers were on the expedition of the Argonauts.

Castor and Pollux saved their sister Helen (Ἑλένη) (Helénē) of Troy.

There are different stories about Dioscuri.

Tyndareus.

Tyndareus (Τυνδάρεος,) was a king of Sparta. His parents were Oebalus and Gorgophone. 

Spartan king married Leda, the Aetolian princess. Tyndareus was the father of Castror, Philinoe, Phoebe, Clytemnestra, and Timandra.

He met with other characters, gods, and goddesses, such as: Heracles, Aphrodite, Agamemnon, Menelaus, Helen of Troy, Odysseus, and etc.

Clytemnestra.

 Clytemnestra (Κλυταιμνήστρα) was known as the wife of Agamemnon, king of Mycenae, in Greek legends. Her parents were Tyndareus (Τυνδάρεος) and Leda. Clytemnestra's sister was Helen of Troy.

She had relations with other characters, such as: Aegisthus, Achilles, Artemis, and etc.

She killed her husband Agamemnon.

Clytemnestra had several children: Orestes, Electra, Aletes, Erigone, Chrysothemis.

Her son Orestes killed his mother. Clytemnestra was buried away from the city wall of Mycenae.

Artists and sculptors created different paintings and sculptures about this character.