The Odyssey, book 10.
Circe, as seen in the Oddyssey. Ulisses comes upon her island in one of his travels, and it is in that island that she turns his fellow sailors to pigs.
She turns them into swine. [AKA pigs]
Circe fell in love with him, so she didn't turn him into a pig
Circe turned Odysseus' men into swine because she did not like men, so she lured them to her island and fed them, and then BAM! They were swine.