In Greek mythology, Eumaeus, or Eumaios, was Odysseus' swineherd before he left for the Trojan War.

In the Odyssey, Eumaeus is the first person Odysseus meets after his return to Ithaca. Although he doesn't recognize his old master in disguise, Eumaeus still treats him well, giving him food and shelter. Eumaeus also welcomes Odysseus' son Telemachus when he returns from his voyage to Pylos and Sparta and Telemachus also does not recognize his father at first. During Odysseus' absence Eumaeus had acted as a father to Telemachus.

Despite being a swineherd, Eumaeus was fairly wealthy and could afford to buy his own slave. However, the suitors of Penelope had abused him, taking his best pigs for their own feasts and leaving him with only piglets to eat. Later, when Eumaeus finally recognizes Odysseus, he helps Odysseus kill the suitors.

Interestingly, Eumaeus is the only character in the Odyssey whom the narrator addresses in the second person, as δι Ευμαιη, "you, Eumaeus." He is also frequently called the "noble swineherd."

Desciption of the house of Eumaeus, Odyssey Book 14

He found him sitting in the front part of his house,
a built-up courtyard with a panoramic view,
a large, fine place with cleared land all around.
The swineherd built it by himself to house the pigs,
property belonging to his absent master. 
He hadn't told his mistress or old man Laertes.    
He'd made it from huge stones, with a thorn hedge on top 
and surrounded on the outside with close-set stakes
facing both ways, made by splitting oaks apart
to leave the dark heart of the wood.  Inside the yard,
to house the pigs, he'd packed twelve sties together.
In each one fifty wallowing swine were penned,
sows for breeding.  The boars, far fewer of them,
stayed outside.