1) The Crystal Palace/Brighton & Hove Albion rivalry
As the hilarious video above tells you, this sporting rivalry started in earnest the mid 1970s when Brighton were managed by Alan Mullery and Palace had Terry Venables in charge. The managers didn't like each other from their time together playing with Spurs but it ramped up as the 2 sides fought for promotion from Division 3. An FA Cup 2nd replay game played in Stamford Bridge saw Palace win n controversial fashion and Mullery was fined £100 for his indiscretions. The rivalry remained as both sides fought for promotion in subsequent years. When Mullery was appointed manager of Palace in the early 80s, fans organised a boycott. He lasted 18 months but the fans of both clubs still hate each other.
2) The Banjo Bowl
Thanks to the mighty efforts of South Park, Canadians have a reputation as friendly souls. This isn't the case in the CFL's "Banjo Bowl" rivalry between the Saskatchewan Roughriders and the Winnipeg Blue Bombers. They aren't local rivals ( it takes over 7 hours to drive from Regina (home of the Roughriders) to Winnipeg, so how did the rivalry begin? It flared up when Winnipeg's kicker Try Westwood told assembled media in 2003;
"I had referred to the people of Saskatchewan as a bunch of banjo-picking inbreds. I was wrong to make such a statement, and I'd like to apologize. The vast majority of the people in Saskatchewan have no idea how to play the banjo."
And with that comment, the CFL's biggest rivalry was born. It helped to have the handy "Banjo Bowl" title begging to be picked up.
3) The Seb Coe - Steve Ovett Class War
That two world class middle distance runners from England were rivals isn't strange at all. That the rivalry was played out in 1980s Britain almost exlusively in class terms most certainly was. Ovett, a northerner from a poor background, raced Coe, a southerner from a privileged background on only 6 occasions in the their career and two of them were in Olympic finals! While they both try and play it down these days, there's no denying that 2 of the world's best middle distance runners did all they could to avoid each other. In the 1980 Olympic 800m final, Ovett shocked Coe to win gold, only for Coe to create his own shock days lter by winning the 1,500m
4) The BYU/Utah Utes Holy War
While this rivalry is certainly local, the unusual part is the fact that it's based on one side's religious beliefs. There are many, many examples of rivalries based on teams/clubs/organisations having differing religious beliefs but this rivalry is based on Brigham Young (BYU) being a Mormon university. Fans of the the secular, state run University of Utah openly mock the church owned School and their moralistic "code of conduct" by being as unsociable as they can be. BYU fans aren't allowed respond with their own bad language or violence so the fans rivalry is pretty one sided. On the pitch though, BYU are pretty competitive.