Houdini assisted with the American war effort during WWI.

Although he was born in Hungary, Houdini was an American patriot and staunch supporter of U.S. involvement in World War I. He persuaded the Society of American Magicians to sign loyalty oaths to President Woodrow Wilson, and later canceled his touring season to devote himself to entertaining soldiers and raising money for the war effort. Houdini also drew on his arsenal of magician’s tricks to provide special instruction to American troops. In a series of classes held at New York’s Hippodrome, he counseled doughboys on how to escape sinking ships and extricate themselves from ropes, handcuffs and other restraints in the event of capture by the Germans.

He owned his own movie studio.

Houdini’s brief career as a silent film star began with 1919’s “The Master Mystery,” an adventure serial in which he played an undercover agent who uses his escape skills to thwart criminal plots. The series was a blockbuster hit—it’s now remembered as the first film to feature a robot—and the magician went on to star in two more features before launching his own studio called the “Houdini Picture Corporation.” He made two films for the company, “The Man From Beyond” and “Haldane of the Secret Service,” but neither fared particularly well at the box office, and critics poked fun at his stilted performances. Having lost a large chunk of his personal fortune, Houdini quit the movie business for good in 1923.

Houdini debunked psychics and the supernatural.

As the world’s greatest trickster and illusionist, Houdini had little patience for anyone who claimed to be in possession of supernatural powers. Beginning in the 1920s, he embarked on a second career as a professional skeptic and debunker of psychics, mind readers, mediums and other “Spiritualists” who purported to be able to contact the deceased. Houdini campaigned tirelessly, often visiting séances in disguise to expose their ringleader as frauds. He also offered a $10,000 reward to any psychic who could present “physical phenomena” that could not be explained rationally (no one ever collected), and in 1926 he testified before Congress in support of a bill to outlaw the practice of “pretending to tell fortunes for reward or compensation.”

The cause of his death is still debated.

Houdini died on Halloween 1926 at the age of 52, just days after struggling through a final performance in Detroit. The official cause of his death was peritonitis brought on by a ruptured appendix, but several legends continue to swirl around his last days. The most famous concerns an incident that had occurred after a performance in Montreal on October 22. While holding court in his dressing room, Houdini was approached by a university student who inquired about a rumor that he could withstand heavy punches to his abdominal muscles. When Houdini boasted about his physical strength, the young man walloped him in the stomach without warning, leaving him doubled over in agony. Houdini complained of stomach pains for the rest of the day, leading many to conclude that the unexpected blows somehow triggered his appendicitis. Others, meanwhile, allege that the great magician was poisoned by the Spiritualists, who had previously issued several death threats against him in response to his attacks.

“Houdini séances” are still held every Halloween.

Despite his skepticism about the spirit world, Houdini swore to his wife Bess that he would try to contact her from beyond the grave. He told her to listen for a specific message—a series of codes that spelled out the words “Rosabelle, believe.” Bess Houdini eventually spent a decade trying to contact her husband before giving up, supposedly saying, “ten years is long enough to wait for any man.” Others continued the search, however, and since the 1930s, fans have held Houdini séances every Halloween to attempt to communicate with the magician’s ghost. There is even an “Official Houdini Séance” that takes place in a different city each year.