Related Clues:

• Nixon kept a list of these
• Shinedown song about foes
• See mine blowing up foes
• G.I. Joe and Cobra Commander, e.g
• Hamilton and Burr, notably
• The Hatfields and the McCoys, e.g
• North and South Korea, e.g
• Poison Ivy and Mr. Freeze, to Batman
• "Them," to "us"
• Spider-Man and Doc Ock, e.g
• Foes see mine explode
• They may be sworn or bitter
• Members of the Legion of Doom, to members of the Justice League
• Yankees and Red Sox, e.g
• Communists and capitalists, e.g