Sarpedon

One of the cases most commonly cited is the fight of Tlepolemos and Sarpedon.

Suppose that I am not Sarpedon, the son of Zeus, nor able to speak in this noble way.

But Ajax slew Epicles, a comrade of Sarpedon, smiting him on the head with a mighty stone, and crushing all the bones of his head.

And so the battle raged, till no one would have known the great Sarpedon, so covered was he with spears and blood and dust.

The master of gods and men expressly declares that he cannot prevent his son Sarpedon from dying at the time appointed.