While many sports fans might not admit it, it can be as fun to have a good rivalry as it is to have a good team. Games against a franchise’s bitter enemies are usually the most thrilling. That goes double for playoff games. Friendly — and not so friendly — rivalries can add a layer of excitement for both the teams and the fans.

24/7 Wall St. reviewed the histories of teams in the NFL, NBA, NHL, and MLB to rank the 20 most exciting and intense rivalries in pro sports. The listed matchup history and other statistics referenced came from the Sports Reference family of sites.

Most of these rivalries are between teams that are in the same division or conference, ensuring they play each other frequently and compete for the same playoff spot.

Even if these teams aren’t in the same division or conference, many of the rivalries on this list are between two teams that are geographically very close to each other. The hatred between these teams and their fans can be fueled by a broader cultural conflict between neighboring cities, such as Los Angeles and San Francisco, Detroit and Chicago, or Montreal and Toronto. These are the best cities for sports fans.

These feuds can sometimes lead to ugly fights, bad blood, and even violence outside of the games themselves. But they can also add to the significance of specific moments in sports, and many of these rivalries have been the source of some of the most exciting moments in sports history. These are the most iconic sports moments of the decade.

Each NHL rivalry has existed since before the league changed its rules, from allowing ties to ending games with shootouts. To avoid confusion, overtime losses were added to the team’s loss total, and ties are the third figure listed in the record for NHL rivalries.

Click here to see the biggest rivalries in sports.