The Moldavian massacre - Dynasty

"Perhaps the most famous Dynasty cliffhanger is the so-called "Moldavian massacre", when Blake's youngest daughter Amanda Carrington married Prince Michael of Moldavia on the eve of a military revolution in his country. Although the massacre itself (arrived at by writer Camille Marchetta, who had devised the wildly-successful 'Who Shot J.R.?' scenario on Dallas five years earlier) had superb production qualities and became the most talked-about episode of any TV series during the calendar year of 1985 (with a viewership of sixty million), it is nonetheless largely remembered for its disappointing resolution four months later.
Nearly every character was in attendance at the royal wedding in the season's final episode which aired in May 1985. At the conclusion of the wedding, revolutionaries stormed in, apparently gunning down everyone in the chapel. The final scene of the episode, with nearly every character on the ground appearing lifeless, gave the impression that anyone could have died, and in the summer that followed many magazines published stories speculating about which characters would survive the massacre.
When the series resumed in the fall viewers quickly learned the outcome of the fifth season finale, where it was revealed that everyone had survived with the exception of two minor characters: Steven's boyfriend, Luke Fuller, and Jeff's girlfriend, Lady Ashley Mitchell (played by Ali McGraw). In the 2006 CBS special Dynasty Reunion: Catfights & Caviar, Gordon Thomson reiterated that it was the follow-up that was the letdown, not the cliffhanger itself. Joan Collins had been conspicuously absent from the season six opener; she was in a tense contract renegotiation with the show, seeking an increased salary. As a result, the first episode had to be rewritten to explain her absence and many scenes were given to Krystle. Collins's demands were met (she reportedly signed a $60,000 per episode contract) and she returned to the series in the season's second episode." wiki