It is said that Jacques de Molay, the last Grand Master of the Knights Templar who was burned at the stake for heresy, imprecated his accusers, Pope Clement V and King Phillip IV of France (and his descendants), as he died.  Apparently, Pope Clement died 33 days after de Molay and King Phillip shortly thereafter, and King Phillip's sons died young, failing to produce male heirs, so King Phillip's dynasty ended.  It seems de Molay's imprecation proved to be very powerful.