Walter Elias Disney was an iconic and highly influential cartoonist and filmmaker in the 20th century. His works have been seen by billions, and his company continues to produce new popular and influential films, cartoons, TV series and more. At the time of his death, Disney was at the height of his success. His film empire was thriving, his Disneyland theme park was growing by leaps and bounds, and he was in the process of developing an even more grand amusement park in Florida. But Walt Disney died very suddenly at age 65. So what happened?

Disney passed away on December 15th, 1966, near his home in Burbank, California. He was interred at Forest Lawn Memorial Park in Glendale,, California, just a few miles away. In the months leading up to his death, Disney discovered that he had a malignant tumor on his left lung. This was discovered by doctors who performed an x-ray for an unrelated neck surgery.

Sadly, the tumor was discovered on November 2nd of 1966, and though Disney was given a life expectancy of 6 months to 2 years, he would not make it through the following month. Doctors removed the affected lung and performed chemotherapy on the ailing Disney. On November 30th, Disney collapsed in his home and was rushed to the hospital, where he remained for the next two weeks until his death.

On December 15th, Disney died. His cause of death was acute circulatory collapse, brought on the by lung cancer. He died 10 days after his 65th birthday. His Florida theme park would later open as planned, and it was named “Walt Disney World” in his honor.

Disney's lung cancer was arguably the result of years of smoking, but although his death was truly premature and tragic, his legacy lives on with future generations who enjoy his classic works as well as new adventures like “Tangled,” “Wall-E,” “Toy Story” and “The Princess and the Frog.”

But here is an odd bit of trivia. Shortly before he died, Disney wrote down the name of the actor Kurt Russell. This used to be a long held urban legend, but on a 2007 episode of Jimmy Kimmel Live, the actor confirmed the rumor to be true, saying “I don't know what to make of that.” Russell recalled being brought into Disney's office, where he was shown the mysterious scribbling.