The Superman Curse has supposedly cast a number of misfortunes on people involved in the Superman franchise over the decades, from career ruin to death.
First there's George Reeves, who played Superman in the 1950's TV series Adventures of Superman. He was found dead in 1959 of a single gunshot wound to the head. The death was ruled suicide but his fingerprints were never found on the gun, so unless he shot himself with his feet (and that's some length to go to just to screw the insurance company) it was probably murder.
Then of course there's Christopher Reeve--eerily similar surname, eerily similar bad luck. After success in four Superman films he was thrown form his horse in 1995, leaving him paralyzed from the waist down and demonstrating vividly the reasons mankind has largely abandoned horses as a mode of transportation.
Slightly less severe misfortune landed on Richard Pryor who, if being in Superman III wasn't misfortune enough, was later diagnosed with Multiple Sclerosis. Then you have Margot Kidder (Lois Lane) who suffered from bipolar disorder and Marlon Brando (Jor-El) who withdrew from society and dedicated himself to becoming the fattest man on earth.
On the outer edges of the Curse Zone we've got various actors who starred in Superman adaptations and had their careers die on them afterwards. Dean Cain, who played Superman in Lois & Clark, is one example. Those who don't believe in the curse often point out that Cain's co-star Teri Hatcher later went on to star in the long-running TV show Desperate Housewives. On the other hand, those who do believe in the curse often point out that Teri Hatcher later went on to star in the long running TV show Desperate Housewives.
So what caused this one? Did they disturb another ancient burial ground? Well, we like to think the curse was called down by Jerry Siegel and Joe Shuster, the two people who created Superman. Having created one of the country's most beloved superheroes while under contract to DC Comics, they were completely screwed out of the royalties.
In 1975 the couple finally were begrudgingly awarded a yearly pension from Warner, DC's parent company, who wanted to avoid bad publicity prior to release of the first film. Though, apparently, the 35 grand a year they paid out wasn't enough to offset the bad karma.
Siegel & Shuster ain't nothin' to fuck with.
That, or the "curse" is just a series of meaningless coincidences.
Most Tenuous Link to the Curse:
According to inside sources, (again, Wikipedia), "In 1963 John F. Kennedy's staff approved of a Superman story in which the hero touts the president's physical fitness initiatives, scheduled to be published with an April 1964 cover date. On November 22, Kennedy was shot and killed." To our knowledge, this is the first time Superman has been touted as the second gunman.