Brutus and Antony, e.g.

• All the people attacking you
• People on a Nixon list
• Ones at the gate, maybe
• Napoleon and Wellington
• Bitter rivals
• The Hatfields and the McCoys, e.g
• The other side
• Gophers and gardeners, say
• The Bloods and the Crips, e.g

Wiktionary Word definitions in Wiktionary
n. (enemy English)