Curse of the Billy Goat
The Curse of the Billy Goat was a long-standing "explanation" of why the Chicago Cubs did not win a National League pennant for decades. Supposedly, Bill Sianis, owner of the Billy Goat's Tavern, and his pet goat, were kicked out of Game 4 at the 1945 World Series after some other spectators complained about the goat's odor. Sianis cursed the Cubs, who did not return to the World Series until 2016. 52 years after the curse was supposedly laid, in 1997, Bill's son Sam (then owner of the tavern) and a new goat were brought in by the Cubs to rid them of the curse, but seemingly in vain.
In his final column, Mike Royko wrote: "It's about time that we stopped blaming the failings of the Cubs on a poor, dumb creature that is a billy goat... blame for many of the Cubs' failings since 1945 can be placed on a dumb creature. Not a poor, dumb creature, but a rich one...P.K. Wrigley." Royko noted that the Cubs integrated long after other teams, costing them a chance to remain competitive through the 1940s and 1950s and leaving them years behind teams like the Brooklyn Dodgers and Cleveland Indians who integrated and won titles.
The bizarre circumstances under which the Cubs failed to reach the 2003 World Series, in the infamous "Steve Bartman game" against the Florida Marlins in the 2003 NLCS, made fans wonder whether the curse was even more powerful than anyone had thought. The Cubs were very competitive during the regular season in the ensuing years, but folded as soon as the postseason started - more evidence of caprine voodoo.
After the famous bust of KFC founder Colonel Saunders was found in a river in Osaka (the curse of Colonel Saunders, see the Hanshin Tigers article), KFC offered to bring the brittle statue to Chicago for Opening Day 2009 to help the Cubs lift the Curse of the Billy Goat. 
The curse was still on fans' minds when the Cubs threatened to return to the postseason in 2015, on the back of new generation of young players. Competitive eater Takeru Kobayashi and three colleagues tried to exorcise the curse by eating an entire goat - 40 pounds of meat - in a twelve-minute seating on September 22nd.
It's not sure what event transpired to finally lift the curse in 2016: the Cubs were simply the best team in baseball by a long shot that year, winning 103 games, and then won the first two rounds of the postseason without being seriously threatened (even though the Los Angeles Dodgers did take a short-lived two games to one lead in the NLCS before losing the next three contests). When the Cubs won Game 6 on October 22nd, the curse was officially broken, just like the famed "Curse of the Bambino" had been lifted by the 2004 Boston Red Sox seemingly without any extraordinary intervention.
- John C. Skipper: The Cubs Win the Pennant!: Charlie Grimm, the Billy Goat Curse, and the 1945 World Series Run, McFarland, Jefferson, NC, 2004.