In Greek mythology, Eumaeus, or Eumaios (Εὔμαιος), was Odysseus's swineherd and friend before he left for the Trojan War. He was brought up with Odysseus and his sister Ctimene as a family slave, although he was treated by Anticleia, their mother, almost as Ctimene's equal. In Homer's Odyssey, Eumaeus is the first mortal that Odysseus meets after his return to Ithaca. Although he does not recognise his old master—Odysseus is in disguise—and has his misgivings, Eumaeus treats him well, offering food and shelter to what he thinks is a mere indigent. On being pushed to explain himself, Odysseus spins a distorted tale, misleading Eumaeus into believing that he is the son not of Laertes but of Castor.
The swineherd refuses to accept the vow that Odysseus, whom he loves above all others (rendering him especially bitter towards the suitors), is finally on his way home. Having heard such assurances all too often, and been deceived by a prevaricator from Aetolia, Eumaeus has become inured to them. "Don't you try to gratify or soothe my heart with falsehoods," he cautions. "It is not for that reason that I shall respect and entertain you, but because I fear Zeus, the patron of strangers, and pity you."
God-fearing, suspicious and scrupulous, Eumaeus delivers probably the oldest extant example of literary sarcasm when, after Odysseus offers a bargain entailing that he be thrown off a cliff should he lose, he cries, "Yes! And what fame and fortune I should win for myself in the world, once and for all, if, after taking you into my hut and showing you hospitality, I were to rob you of your precious life! I would be a willing party to a crime against Zeus, son of Cronos, if I did that."
Eumaeus is generous in his offerings to guests and gods (Hermes in particular) and so fair-minded as to strive to divide meals equally between everyone he feeds. The axiom "The god will give, and the god will take away, according to his will, for he can do anything" fairly encapsulates his philosophy.
During his master's long absence, Eumaeus acquires from the Taphians a servant, Mesaulius, with his own ostensibly meagre resources. Mesaulius serves as a waiter during Odysseus's first supper back on Ithaca, in Eumaeus's hut with its owner and his fellow herders.
During Odysseus's absence, Eumaeus acted as father to Telemachus. Interestingly, he is the only character in the Odyssey whom the narrator addresses in the second person, as in "δι Ευμαιη", "you, Eumaeus". He is frequently called the "noble swineherd" and "prince of swineherds" -- perhaps, say some academics, because Homer feels an affinity with him.