People go missing all the time, for all kinds of reasons. Some become famous for disappearing. But sometimes, people who were already famous in their own time just end up vanishing. Like Amelia Earhart.
But we've all heard of her. Here are a few other celebrities that just disappeared.
Spartacus led the biggest and most famous slave revolt in Ancient Rome's history. He was a Thracian (likely born near modern-day Bulgaria), an ex-Legionnaire, and somehow ended up a slave-gladiator. He led a break-out of about 70 fellow slaves, armed only with kitchen supplies. Then he slaughtered or avoided everyone who tried hunting him down, and soon had an army of 70,000 at his command. But the Legions wore away his forces and eventually his rebellion was broken at the battle of Senerchia.
All the remaining captured rebels were crucified. But Spartacus himself was never found, alive or dead. He might have died in battle, but there were also rumors he'd somehow survived, and snuck away back to his home (which was all he really wanted in the first place).
2. Emperor Constantine XI
Constantine XI Palaiologos was the last Emperor of Byzantium. In his reign, the Muslim Turks finally achieved their 700-year goal to conquer Constantinople, the greatest city in the Christian World. Not a bad ruler himself, Constantine was unlucky enough to be born from a long line of screw-ups who had been steadily failing to stop the Muslims from swallowing up their once-great empire. And Constantine's rival, Mehmet II, was a military mastermind. When Mehmet besieged Constantinople with an army ten times bigger than Constantine's, the Emperor refused to surrender. He fought side-by-side with his men holding out for months; when the walls were breached he said "the city is fallen, but I yet live", stripped off his royal vestments, and led his men in a last-stand charge.
In spite of a huge search, the Muslim invaders never found him (or his body). They tried everything, including a large reward.
Constantine probably died, or may have somehow fled. He was never seen again, but Greek freedom-fighters against Turk Muslim rule used his legend for inspiration for centuries to come.
3. Solomon Northrup
Northrup was a freeborn black man from the northern United States. He was kidnapped and sold into slavery in the south, and spent years there before he managed to get help and freedom from his illegal enslavement. He went on to write a book in 1853 called Twelve Years a Slave; it became hugely influential in the abolitionist movement and made him very famous in his own time.
In 1857, he was in Canada, promoting his book. One night, he just disappeared. Rumors claim he'd been killed by anti-abolitionists, or kidnapped again and put back into slavery, or that the strain of his experiences and later fame were too much for him and he just walked away from it all to live the life of an anonymous vagabond.
4. Ambrose Bierce
Ambrose Bierce was widely renowned as the wittiest writer the United States ever produced. A journalist and author, he was considered America's (maybe the world's) greatest satirist from the 1880s onward. His 1911 book The Devil's Dictionary is a masterpiece of satire everyone should read.
Although he was in his 70s when he disappeared in 1914, he was still at the peak of his fame. It would be as if Stephen Colbert were to just disappear today.
Ever an adventurer, Bierce went to Mexico to report on Pancho Villa's revolution. He was in Chihuahua in January 1914, wrote a friend that he was going to an "unknown destination", and then just vanished.
Some think he was killed by one side in that conflict, or died on a journey from complications due to his chronic asthma. Others think maybe suicide. No hard proof was ever found.
5. Harold Holt
If you're American you probably never heard of him. Holt was Prime Minister of Australia. He became PM in 1966, and vanished while still in office on December 17th, 1967.
Holt was an avid swimmer. One day he was with friends at Cheviot Beach and got in the water, and that was it. A massive search was undertaken, but no trace was found. While most people presume he drowned, some suggested he might have committed suicide; and some conspiracy theorists claim he actually defected to China, and got into a waiting Chinese submarine.
Imagine the chaos that would erupt if a sitting US President were to suddenly disappear like that! But Australians are different. In fact, in a touch of very dark humor, they honored his memory by naming a Swim Center in Melbourne after him!
6. Oscar Zeta Acosta (a.k.a. Dr. Gonzo)
Acosta was a writer, lawyer and Chicano activist, but became famous mainly due to his friendship with the writer Hunter S. Thompson. Thompson immortalized him as "Dr. Gonzo" in the heavily-embellished account of a trip the two took together in 1971. You know, Fear & Loathing in Las Vegas; the greatest American novel of the baby-boomer generation.
Acosta's the guy Benicio Del Toro's character was based on.
In 1974, only two years after the book made him famous, he took a trip to Mazatlan, Mexico. He vanished. His last message, to his son was that he was about to get "on a boat full of white snow." Some people think he overdosed. Thompson thought he may have been killed by drug dealers or by law enforcement. Of course, he was "too weird to live, and too rare to die," so who knows? He may still be out there somewhere.