Communists and capitalists, e.g

• Adams and Jefferson, e.g.
• Shinedown song about foes
• The other side
• Allies' antitheses
• Spider-Man and Doc Ock, e.g
• Alexander and Darius
• Pakistan and India, e.g.
• Allies, to the Axis

Wiktionary Word definitions in Wiktionary
n. (enemy English)