Hercules v. Cerberus

Hesiod, Theogony 310 ff (trans. Evelyn-White) (Greek epic C8th B.C.) :

Typhaon . . . was joined in love to Echidna. . . And next again she bore the unspeakable, unmanageable Kerberos, the savage, the bronze-barking dog of Hades, fifty-headed, and powerful, and without pity.

Ovid, Metamorphoses 7. 412

There is a cavern yawning dark and deep, and there a falling track where Hero Herakles of dragged struggling, blinking, screwing up his eyes against the sunlight and the blinding day, the hell-hound Cerberus, fast on a chain of adamant.

His three throats filled the air with triple barking, barks of frenzied rage, and spattered the green meadows with white spume…..

Pseudo-Apollodorus, Bibliotheca 2, 125 (trans. Aldrich) (Greek mythographer C2nd A.D.)

Herakles asked Hades for Kerberos and was told to take the hound if he could overpower it without using any of the weapons he had brought with him.

He found Kerberos at the gates of (Acheron), and there, pressed inside his armour and totally covered by the lion’s skin, he threw his arms round its head and hung on, despite bites from the serpent-tail, until he convinced the beast with his choke-hold.

Then, with it in tow, he made his ascent through Troezen.

After showing Kerberos to Eurystheus, he took it back to Hades’ realm.