March 19, 1871 - January 30, 1889: Age 17
If bad judgement were consistently fatal, we would never live beyond our teenage years. Mary Vetsera, the teenaged progeny of an elderly Baron and the daughter of a low-class Greek millionaire, made a lot of silly choices just like any other teenager, but in her case they were fatal.
Encouraged by her ambitious mother, she attracted the attention of Rudolph, the Crown Prince and heir of the Austrian Empire. Had he lived today he would have been all over the tabloid press: unable to connect with his distant, narcissictic mother (see September 10 death) and rigid, conservative father; and distant from all others due to his exalted rank, he drowned his depression and frustration in champagne, ether, opium, and sex. At 30, the physical effects were beginning to tell: he had contracted syphilis (which he had passed on to his wife and, no doubt, many others as well) and suffered blinding headaches and seizures. Married and emotionally unstable, he was not a great catch.
Mary seems to have been blinded by love and by the sheer romance of the lonely, great man, desperate for her tender rescue. Their relationship was consummated in mid-January. When he proposed a suicide pact with her, she agreed, and began composing suicide notes for various family members immediately (some were even found before the death). What she probably never knew was that she was not his first choice: Rudolph had been shopping for some time for a companion in death. Previously he had asked (many times) his friend Mitzi Kaspar, a Viennese prostitute, to join him. She, sensibly, refused and reported it to the police, who did nothing.
On the evening of January 30, 1889, Rudolph and Mary met at his hunting lodge, having agreed to spend one more night together before plunging into the afterlife together. At some point during the night Rudolph shot Mary. He then stayed in the room with the body six to eight hours before shooting himself in the head.
Because of his political position, the prime directive to all involved was instantly understood to be "cover-up". Mary's body was smuggled out of the lodge and buried secretly at a nearby monastery, her relatives warned, even threatened, to keep quiet. The first official story was that Rudolf had died of a heart attack. Too many servants, however, had seen the bodies and the notes for that to hold up, however, and the story of the suicide pact quickly became widespread. A special dispensation was obtained from the Pope to bury Rudolph in the family tomb (normally suicides cannot be buried in sacred ground).
Later various stories surfaced about conspiracies, some alleging that the couple had been killed by French spies, others that the Emperor himself had ordered the deaths. It is not known for sure how Mary died; officially she was said to have been shot, but other stories state that she was strangled. Her remains were stolen in 1992; when returned they were examined and there was no evidence of a gunshot but there was evidence of a severe beating. However it cannot be known for sure if the 100-year-old skeleton was actually hers. Some reports say that only one shot was fired, killing Rudolph; others say that six shots were fired. Because the crime scene was cleared up with only brief examination, and because the Emperor spent a fortune silencing witnesses and suppressing evidence, the truth will never be known.
Sources: Wikipedia, The Mayerling Tragedy