A large number of people go missing every day. These disappearances are often caused by murders, kidnappings, and sometimes the person simply runs away and changes their identity. In most cases, these cases are solved, and the people are found, but sometimes that doesn't happen. All that can be done is theorize and speculate, but without hard evidence or useful information, solving the case is virtually impossible. Here is a list of ten such people who mysteriously disappeared and were never found.
1. Harold Holt
In 1967, Australia's 17th Prime Minister, Harold Holt, went for a swim and was never seen again.

On December 17, 1967, the 17th Prime Minister of Australia, along with his alleged mistress and three other friends, went to Cheviot Beach in Victoria for a swim. The others soon lost sight of him, and fearing the worst, the Royal Australian Navy and Air Force conducted a thorough two-day search, but to no avail. Authorities were forced to declare him dead.
There are several theories regarding the cause and circumstances of his death. In 2005, the coroner suggested that accidental drowning may have been the cause. It was also reported that in September 1967, Holt was suffering from shoulder pain and was advised not to play tennis or swim, which he ignored. In a 2007 documentary, «"Who Killed Harold"» It has been suggested that suicide could be another possible reason for Harold's disappearance. (source)
2. D.B. Cooper
In 1971, he hijacked a Boeing 727 and, after receiving a ransom of $200,000, parachuted out, disappearing forever and never being seen again.

On November 24, 1971, D.B. Cooper boarded a Boeing 727 en route from Portland, Oregon, to Seattle, Washington. He hijacked the plane, demanded a $200,000 ransom, and parachuted to his death. The FBI spent years trying to solve the most mysterious hijacking in American aviation history.
Numerous theories have been put forward by various people, but recently, Marla Cooper, his niece, claimed to have seen her uncle after the night of the hijacking and that he had suffered multiple injuries. Marla also assisted the FBI by providing her uncle's guitar strap with fingerprints on it, as well as a photograph of D.B. Cooper. However, fingerprint testing was inconclusive. According to an ABC News article, Marla's mother made a similar claim in 2011, saying she also believed her son-in-law was the infamous hijacker. (source)
3. Bobby Dunbar
Dunbar disappeared when he was four years old. Police later found the boy, and he was reunited with his family. Nearly a century later, DNA testing irrefutably proved that the child they rescued was not Bobby Dunbar.

On August 23, 1912, the Dunbar family went fishing on Lake Swayze in Louisiana when Bobby disappeared. Investigators conducted an eight-month search and finally found the boy in Mississippi, living with William Walters and Julia Anderson. The Dunbars claimed he was their missing son. Although the Andersons protested, claiming he was their son, Charles Bruce Anderson, a court ultimately ruled in the Dunbars' favor. It was believed this was partly because Julia Anderson couldn't afford a lawyer. However, in 2004, a second DNA test determined that the boy who was with the Dunbars was not their blood relative. The test was conducted between Bobby Dunbar Jr. and his supposed cousin, Alonzo Dunbar Jr., but the DNA results were inconsistent. (source)
4. Jim Sullivan
Musician Jim Sullivan, who recorded an album in 1969 called UFO , containing cryptic texts about deserted highways and strange lights, disappeared six years later. His car was later found abandoned on a deserted road.

Jim Sullivan, an American songwriter, singer, and guitarist, typically sang about deserts, UFOs, highways, and aliens. One of his songs describes an alien abduction, and his debut album was called UFO. On March 4, 1975, he left Los Angeles and drove to Nashville in his Volkswagen Beetle. The next day, he checked into a motel in Santa Rosa, New Mexico, and reportedly bought vodka at a local store, but did not stay overnight and left his key in his room. The following day, he was seen at a remote ranch 26 miles away, where his car was found abandoned. He left all his money, guitar, clothes, and a box of unsold records in the car and left, never to be seen again. (1, 2)
5. Felix Moncla
Moncla was a US Air Force pilot who went missing in 1953 while investigating an unusual radar target. Those watching the radar screen saw his plane appear to merge with the target, as if colliding with it, but no wreckage or bodies were ever found.

On November 23, 1953, Air Defense Command ground intercept radar operators detected an unusual target near Sioux Locks, Sault Ste. Marie, Michigan. A jet from Kinross Air Force Base, piloted by 1st Lt. Felix Moncla, was dispatched to investigate, with 2nd Lt. Robert L. Wilson operating the radar.
Although Wilson had trouble tracking the aircraft, he eventually managed to guide the Moncla toward the target at an altitude of approximately 8,000 feet. Soon, the two dots—the target and the aircraft—aligned on the radar screen and remained in place. Fearing a collision, the operators unsuccessfully attempted to contact the Moncla by radio, and the US Air Force and Canadian Air Force dispatched search and rescue teams. However, they were unable to locate any trace of either the pilots or the aircraft. (source)
6. Gedhun Choekyi Nima
In 1995, a six-year-old Tibetan boy was elected Panchen Lama, Tibet's second-highest Buddhist leader. He was later arrested by the People's Republic of China, and no one knows his whereabouts.

On May 14, 1995, six-year-old Gedhun Chökyi Nyima was proclaimed the 11th Panchen Lama by Tibetan Buddhists and recognized by the Dalai Lama. Upon learning of this, Chinese authorities arrested him, and he has not been seen since. Although the Chinese nominated another boy, Gyankyain Norbu, for the post of Panchen Lama, the majority of Tibetans and the Buddhist community rejected this decision. According to The Guardian , a Chinese official said Gedhun Choekyi Nyima "is alive, receiving an education, growing up healthy, leading a normal life and does not wish to be disturbed.". (source)
7. Frederic Valentich
In 1978, pilot Frederick Valentich went missing along with his plane after a collision with a mysterious UFO. His last message was: «"Melbourne, that weird flying machine is hovering over me again... (two seconds, microphone open) ...it's hovering, and it's not a flying machine..."»

Frederick Valentich, a "flying saucer enthusiast," went missing during a 125-mile training flight in a Cessna light aircraft over Bass Strait, Australia, on October 21, 1978. On his final flight, he claimed to be accompanied by another aircraft flying approximately 300 meters above him, although he later stated, "It's not an aircraft.".
Many reported UFO sightings in Australia on the night of his disappearance, although officials were skeptical that a UFO was behind Valentich's disappearance. Another explanation is that Valentich became disoriented and saw his own lights reflected in the water or the lights of a nearby island while flying upside down. (source)
8. Henry Hudson
English explorer and navigator Henry Hudson, his teenage son, and several loyal crew members were abandoned by the rest of their crew in an open boat. Despite numerous searches, they were never found.

Henry Hudson was a renowned British explorer, after whom several places are named. In June 1611, during an expedition, his homesick, cold, and starving crew wanted to return to England after several months spent on the ship in Hudson Bay. However, Hudson refused, wanting to continue exploring and discover a passage to Asia. This decision led to a mutiny among the crew. They abandoned Hudson, his teenage son John, and seven other crew members in an open boat with clothes, gunpowder and shot, pikes, an iron kettle, and a small amount of meat to survive.
There are no reliable accounts of what actually happened. Some claim the mutinous crew killed him, along with his son and loyal crew members. Others say he, like everyone else, froze to death. The crew returned to England, stood trial, and were found guilty. Although they were arrested and charged with treason and the murder of their captain, they were never punished. (source)
9. Granger Taylor
Taylor left a note for his parents saying he was going on an interstellar voyage with aliens for 42 months. He never returned.

Granger Taylor lived with his parents on their farm in Duncan, a small town on southern Vancouver Island. He was well known among neighbors and friends as a UFO enthusiast. On the evening of November 29, 1980, 32-year-old Granger Taylor left an ambiguous note stating that he was embarking on an interstellar journey in an alien spacecraft.
The note read:
«"Dear Mom and Dad,
I embarked on a journey on an alien spaceship because recurring dreams foretold a 42-month interstellar voyage to explore the vast universe, after which I would return. I leave you all my property, as I will no longer need it. Please use the instructions in my will as a guide.
With love, Granger.
Taylor was never found after that. No one knows whether he actually made interstellar travel or not. But the most common claim is that he was mentally unstable following his father's recent accident. He dropped out of school in the eighth grade and worked in local mechanic shops. His fascination with UFOs, mental instability, and obsession with mechanics were obsessive. (source)
10. Louis Le Prince
Le Prince was a French inventor who captured the first moving images and is considered the father of cinematography. In September 1890, he took a train to Paris, during which he disappeared along with his inventions.

In September 1890, Louis Le Prince planned to travel to Britain to patent his new camera, and then to the United States to promote it. But first, he wanted to visit his friends and family, which he did. On September 13, he left Bourges and went to Dijon to meet his brother. On September 16, he boarded a train from Dijon to Paris, but when the Dijon-Paris express arrived, his friends discovered he was gone. Neither his luggage nor his body were ever found, and no one noticed anything strange or suspicious on the train.
Several theories have been put forward to explain his unusual disappearance. Some claim he committed suicide after testing his invention again and finding it ineffective. Others suggest he was murdered to prevent him from patenting his invention. Another theory suggests he disappeared due to financial difficulties. Yet another suggests his brother from Dijon may have murdered him before he boarded the train. (source)
