9. Bobby - All My Children
Bobby Martin was the twelve-year-old son of Dr. Joe Martin, and his only real crime was having brothers and sisters. Ultimately, the producers of the show decided that there were too many Martins running around, and they wrote off little Bobby.
They sent him up to the attic to get his skis (never mind the fact that he was about to head off to summer camp...water skis maybe?) and he just never came back downstairs again. The most galling part about this whole mess is that it's a soap opera. There are literally limitless possibilities to write off characters. You don't want a character around anymore? Fine. Have him die from a rare blood disease, or get eaten by a werewolf, or fall down a well for ten years until the character could be played by an adult actor and not have to deal with pesky child labor laws.
The world is your oyster, All My Children! Creating melodramatic and unrealistic deaths for your unwanted characters is what you were put on earth to do! And you sent little Bobby up to the attic? That's what you came up with? Wasted opportunities. Never let it be said, however, that they didn't have a sense of humor about their writing. Years later, a character went up to the attic, only to find a skeleton wearing a ski cap with the name Bobby on it.