Besides Odysseus, who is the other hero in The Odyssey?
Telemachus could also be counted as a hero in The Odyssey. He stands up to the suitors, men who are quite contented to exploit the rules concerning hospitality and plot Telemachus's death. He is also brave enough to sail out, away from home, to go in search of news of his father, Odysseus. The dutiful son who helps to avenge the wrongs done to his father is very much a hero to the ancient Greeks—Orestes, the son of Agamemnon who slays his mother and her lover after they killed his father, is also revered as a hero.
It's true that Athena helps Telemachus quite a bit, but she—and other gods—help his father, too, and that doesn't make him any less of a hero. In fact, the gods often do not help individuals they find unworthy, so the favor Telemachus finds with Athena is really to his credit. Then, once Odysseus returns to Ithaca, Telemachus bravely assists him in slaying the suitors and reclaiming his rightful place. For these reasons, Telemachus can be seen as a hero as well.
Of course we could list several “heroes” from The Iliad, but the single name from The Odyssey that immediately stands out is Penelope. Not only in her faithfulness and trust that Odysseus will return, but in the way she fends off the suitors while still keeping the Greek codes of hospitality, and the way she teaches Telemachus to love and respect his absent father, are of heroic dimension. Her sacrifice of the protected life the suitors offer her is heroic, as well as her faithful preservation of Odysseus’ reputation, represented by her care with his weapons. Heroism in not always physical sacrifice; it registers in the adherence to ethics, morals, and loyalties in a crisis, in the face of hardship and temptation.
I definitely agree that Penelope is the other hero of the Odyssey. Besides Odysseus, she is portrayed as the human with the strongest will, the most moral outlook, and the most agency. In order to be a hero, one must face complex challenges and difficult choices. Arguably, Penelope faces THE most difficult choice in the entire epic poem. Although Odysseus goes through many trials and tribulations, his path is almost always clear: he wants to get home to Penelope. However, on the other side, Penelope has absolutely no idea if Odysseus is alive or not. Everyone else, even their son Telemachus, has lost hope that he will ever come home. Yet, Penelope retains her absolute trust in his abilities. She could follow the easy path, to choose a suitor and remarry, but she doesn't. Instead, she uses her cleverness to hold the suitors at bay with trick after trick.