When a whole country knows who you are, how can you just vanish off the face of the earth? That's the mystery these 10 famous disappearances pose:

1. Glenn Miller

In the "Big Band" era Miller was a triple threat: he was a composer and band leader, a talented trombone player, and even an actor. His band, the Glen Miller Orchestra, had a string of #1 hits in the '30s and '40s, including "Chattanooga Choo Choo."

But like other celebrities, Miller felt the call to serve his country when America joined World War 2. As an Air Force recruit, Miller held concerts for service members, and he was on his way to a gig in 1944 when his plane vanished over the English channel. No sign of the plane or the 3 people on board was ever found.

2. Dorothy Arnold

A young and wealthy socialite, Arnold was one of the most recognizable people in New York, but that didn't stop her from vanishing without a trace in broad daylight on December 12, 1910. Arnold walked along Fifth Avenue, stopping to chat with friends along the way, before turning into Central Park.

Arnold's body was never found (despite a very thorough search) but police later uncovered she was pregnant when she disappeared. Most theories say that she was murdered by her lover to cover up their premarital affair.

3. Jean Spangler

This young actress was on the verge of her big break in Hollywood when she went missing on the way to see her ex-husband. Police quickly realized he wasn't the culprit, then discovered Spangler's purse with a mysterious note inside.

It read: "Kirk, Can't wait any longer. Going to see Dr. Scott. It will work best this way while mother is away." Many believe that the Kirk in her note is Hollywood star Kirk Douglas, who had co-starred with Spangler in a recent movie. Sadly, Spangler was never seen again.

4. Heinrich Muller

Muller was more infamous than famous, but he was definitely very well-known. He rose through the ranks of the Gestapo, Nazi Germany's secret police, and had a hand in their invasion of Poland and the Holocaust.

But when it was time for Muller and other high-ranking Nazis to face the music, he was nowhere to be found. Muller was last seen in May, 1945, and while many say he died the CIA searched for him in South America. Maybe Muller spent the rest of his life there under an assumed identity.

But Muller wasn't the only person to mysteriously disappear...

5. Ray Gricar

Gricar was a District Attorney from Centre Country, Pennsylvania who disappeared after going for a drive in the countryside. His car was found outside an antique shop, while his laptop was lying in a river nearby.

The investigation into Gricar's disappearance revealed he knew some of the details of the Penn State child abuse scandal, and that he had Googled how to destroy a hard drive days before he vanished. His exact connection to the case and what happened to him are still unknown.

6. Harold Holt

Many people call Holt's disappearance the strangest of all time. He was a popular and successful Australian politician who became the country's Prime Minister in the late '60s. He was swimming at his favorite spot in 1967 when he vanished, never to be seen again.

Of course many think Holt drowned, but he was a strong swimmer. There was no government inquiry into his death, and one rumor suggested he could have been a spy for the Chinese government. But as a friend pointed out, Holt "didn't even like Chinese food."

7. Jim Thompson

Thompson began his career as a spy for the OSS, which later became the CIA. After World War 2 he reinvented himself as a businessman in Thailand, and single-handedly brought the country's silk industry back to life.

One day, Thompson left his home for a short walk, leaving behind his jacket, cigarettes and important medication. He never came home, and while a thorough search was conducted there was no sign of him anywhere. Was Thompson a simple missing person case, or did his spy career catch up with him?

8. Amelia Earhart

A puzzle that continues to stump the world decades after she vanished, Amelia Earhart was the world's most famous pilot when she disappeared during her attempt to fly around the world. On July 2nd, 1937, she reported being low on fuel somewhere over the Pacific.

Earhart was reported as dead 2 years after she went missing, but amateur sleuths continue to dig into her mystery with hopes of discovering exactly what happened. Just this year, new clues to the mystery were discovered.

9. Louis Le Prince

Le Prince was a great inventor who was well-known as a pioneer of the motion picture camera, but today he's remembered for the locked room mystery surrounding his disappearance. Le Prince boarded a train from Dijon, France to Paris, but when the train reached its destination Le Prince and his luggage were nowhere to be seen.

Police investigated his family, who they suspected of being interested in the money from Le Prince's patents, but couldn't prove anything. Some say Thomas Edison, a rival inventor, had a hand in whatever happened to Le Prince.

10. Jimmy Hoffa

With his well-known mob connections, it seems obvious why Hoffa went missing after meeting a pair of gangsters at a restaurant outside Detroit in 1975. But the fact that the union leader's body has never turned up still baffles police.

Hoffa was rumored to have been buried everywhere from a quiet Detroit suburb to Giants Stadium in New York, but so far all of the leads have been dead ends. The FBI is sure Hoffa is dead, but many believe he's still hiding out somewhere.

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