Ithaca is an island in Greece and the home of Odysseus in Homer's Odyssey. See Ithaca.

Several places in the United States of America have been named after this island:

• Ithaca, New York in Tompkins County, New York, home of Cornell University
• Ithaca, Georgia in Carroll County, Georgia
• Ithaca, Michigan in Gratiot County, Michigan
• Ithaca, Nebraska in Saunders County, Nebraska
• Ithaca, Ohio in Darke County, Ohio
• Ithaca, Wisconsin in Richland County, Wisconsin

Ithaca Chasma, an enormous valley on Saturn's moon Tethys, is also named after the island.