Kassandra in the Odyssey

At the beginning of the Odyssey, Phemios appears singing tales of the terrible homecomings of the Achaeans

Od. 1.325-327

“The very famous singer sang among them and they
Sat listening in silence as he sang the murderous homecoming of the Achaeans
Which Pallas Athena had set for them from Troy.”

τοῖσι δ’ ἀοιδὸς ἄειδε περικλυτός, οἱ δὲ σιωπῇ
εἵατ’ ἀκούοντες· ὁ δ’ ᾿Αχαιῶν νόστον ἄειδε
λυγρόν, ὃν ἐκ Τροίης ἐπετείλατο Παλλὰς ᾿Αθήνη.

A scholiast believes that these stories are being told to warn the suitors of pursuing an unrighteous marriage

Schol ad Od. 1.327

“In these stories he is warning the suitors from the story of Kasandra and Ajax not to seek unholy marriages.”

ταῦτα δὲ ἦδε νουθετῶν τοὺς μνηστῆρας ἐκ τῶν περὶ Κασάνδρας καὶ Αἴαντος μὴ ὀρέγεσθαι ἀσεβῶν γάμων. H.

But when the time comes for the example the suitor mentions, Kasandra is left out of the picture

Od. 4.499-511

“Ajax perished with his ash-oared ships.
First Poseidon drove him against the great Guraean
Cliffs and then he saved him from the sea.
He would have avoided death then even though he was hated by Athena,
If he hadn’t shot out an arrogant word as he was greatly blinded.
He said that he would escape the great swell of the sea despite divine will.
And when Poseidon heard him boasting so greatly
He immediately grabbed his trident with his strong hands
And struck the Guraen cliff, splitting it in half.
One part remained where it was, the other fell to the sea,
First where the great-blinded fool Ajax was then waiting.
It carried him down into the endless whirling sea.
And he died there, after drinking the salt water.”

Αἴας μὲν μετὰ νηυσὶ δάμη δολιχηρέτμοισι·
Γυρῇσίν μιν πρῶτα Ποσειδάων ἐπέλασσε
πέτρῃσιν μεγάλῃσι καὶ ἐξεσάωσε θαλάσσης·
καί νύ κεν ἔκφυγε κῆρα, καὶ ἐχθόμενός περ ᾿Αθήνῃ,
εἰ μὴ ὑπερφίαλον ἔπος ἔκβαλε καὶ μέγ’ ἀάσθη·
φῆ ῥ’ ἀέκητι θεῶν φυγέειν μέγα λαῖτμα θαλάσσης.
τοῦ δὲ Ποσειδάων μεγάλ’ ἔκλυεν αὐδήσαντος·
αὐτίκ’ ἔπειτα τρίαιναν ἑλὼν χερσὶ στιβαρῇσιν
ἤλασε Γυραίην πέτρην, ἀπὸ δ’ ἔσχισεν αὐτήν·
καὶ τὸ μὲν αὐτόθι μεῖνε, τὸ δὲ τρύφος ἔμπεσε πόντῳ,
τῷ ῥ’ Αἴας τὸ πρῶτον ἐφεζόμενος μέγ’ ἀάσθη·
τὸν δ’ ἐφόρει κατὰ πόντον ἀπείρονα κυμαίνοντα.
[ὣς ὁ μὲν ἔνθ’ ἀπόλωλεν, ἐπεὶ πίεν ἁλμυρὸν ὕδωρ.]

The primary argument seems to have something to do with generalizing the wickedness of Ajax to all of the Achaeans

Od. 3.132-136

“And then Zeus was really devising a murderous homecoming in his thoughts
For the Argives, since they were not all just or prudent a bit.
This is why many of them suffering a terrible fate
From the ruinous rage of the grey-eyed-daughter of a strong-father
Who sent strife between Atreides’ two sons.

καὶ τότε δὴ Ζεὺς λυγρὸν ἐνὶ φρεσὶ μήδετο νόστον
᾿Αργείοισ’, ἐπεὶ οὔ τι νοήμονες οὐδὲ δίκαιοι
πάντες ἔσαν· τῶ σφεων πολέες κακὸν οἶτον ἐπέσπον
μήνιος ἐξ ὀλοῆς γλαυκώπιδος ὀβριμοπάτρης,
ἥ τ’ ἔριν ᾿Ατρεΐδῃσι μετ’ ἀμφοτέροισιν ἔθηκε.

At least, that’s how another scholiast interprets the absence of a reference to Kassandra in this passage

Schol ad Od. 3.135 HEVQ

“The ruinous rage: “Since they did not stop Lokrian Ajax from raping Kasandra in her tample. Now the rage is [directed at everyone in common, but it is clear that the responsibility for the anger lies with Ajax.”

μήνιος ἐξ ὀλοῆς] ἐπεὶ Αἴαντα τὸν Λοκρὸν οὐκ ἐκόλασαν βιασάμενον ἐν τῷ ἱερῷ αὐτῆς τὴν Κασάνδραν. H.E.V. νῦν μὲν κοινῶς εἰς ἅπαντας τὴν μῆνιν, ἑξῆς δὲ σαφέστερον τὴν αἰτίαν τῆς ὀργῆς δηλοῖ ἐπὶ τοῦ Αἴαντος. Q.

Kassandra does appear in the Odyssey, but only in Odysseus’ story of what Agamemnon says about his death.

Od. 11.421-434

“Then I heard the most pitiable voice of Priam’s daughter
Kassandra—crooked-minded Klytemnestra killed her
Over me. Then I fell to the ground with my hands spread wide
Dying on a sword—but the bitch-face turned away from me
And, even as I was on my way to the underworld,
she wouldn’t close my eyes and mouth with her hands.
There is nothing more terrible or cruel than a woman
Who could put such deeds in her thoughts,
The way this woman devised an unseemly act,
When she planned the murder of her wedded husband.
I would have thought that I would come home happy
To my children and the household servants
But she, by conceiving these murderous ideas,
Has poured shame on herself and those to come later,
On the whole female race of women, even for one who does well.”

οἰκτροτάτην δ’ ἤκουσα ὄπα Πριάμοιο θυγατρὸς
Κασσάνδρης, τὴν κτεῖνε Κλυταιμνήστρη δολόμητις
ἀμφ’ ἐμοί· αὐτὰρ ἐγὼ ποτὶ γαίῃ χεῖρας ἀείρων
βάλλον ἀποθνῄσκων περὶ φασγάνῳ· ἡ δὲ κυνῶπις
νοσφίσατ’ οὐδέ μοι ἔτλη, ἰόντι περ εἰς ᾿Αΐδαο,
χερσὶ κατ’ ὀφθαλμοὺς ἑλέειν σύν τε στόμ’ ἐρεῖσαι.
ὣς οὐκ αἰνότερον καὶ κύντερον ἄλλο γυναικός,
[ἥ τις δὴ τοιαῦτα μετὰ φρεσὶν ἔργα βάληται·]
οἷον δὴ καὶ κείνη ἐμήσατο ἔργον ἀεικές,
κουριδίῳ τεύξασα πόσει φόνον. ἦ τοι ἔφην γε
ἀσπάσιος παίδεσσιν ἰδὲ δμώεσσιν ἐμοῖσιν
οἴκαδ’ ἐλεύσεσθαι· ἡ δ’ ἔξοχα λυγρὰ ἰδυῖα
οἷ τε κατ’ αἶσχος ἔχευε καὶ ἐσσομένῃσιν ὀπίσσω
θηλυτέρῃσι γυναιξί, καὶ ἥ κ’ εὐεργὸς ἔῃσιν.’