Odysseus to Achilleus
Even though Odysseus doesn't have a very big role in the Iliad, it is still useful to think of him as a foil to Achilleus. Although we discourage this in general, in thinking about Odysseus it is useful to think about representations of his character outside the Iliad. From the poems in the Epic Cycle (other poems about the Trojan War, not by Homer, which survive only in summary), and especially Homer's Odyssey, we know Odysseus as a wily trickster, who gets things by his wits that could not be done by strength alone. These representations are relevant because they pick up on and expand the image of Odysseus from the Iliad as seen in the night raid from Book 10 or Antenor's reminiscence from Book 2 about Odysseus's awesome speaking ability. These scenes present Odysseus as an alternative kind of hero. We could never imagine him putting himself in the same situation that Achilleus does.