LOS ANGELES — Richard Knerr, co-founder of Wham-O Inc., which unleashed the granddaddy of American fads, the Hula Hoop, on the world a half-century ago along with another enduring leisure icon, the Frisbee, has died. He was 82.

Knerr died Monday at Methodist Hospital in Arcadia after suffering a stroke earlier in the day at his Arcadia home, his wife Dorothy said.

With his boyhood best friend, Arthur “Spud” Melin, Knerr started the company in 1948 in Pasadena. They named the enterprise “Wham-O” for the sound their first product, a slingshot, made when it hit its target.

A treasure chest of toys followed that often bore playful names: Superball, so bouncy it seemed to defy gravity; Slip ‘N Slide and its giggle-inducing cousin the Water Wiggle; and Silly String, which was much harder to get out of the hair than advertised.

When a friend told Knerr and Melin about a bamboo ring used for exercise in Australia, they devised their own version without seeing the original.

They ran an early test of the product in 1958 at a Pasadena elementary school and enticed their test subjects by telling them they could keep the hoops if they mastered them. They seeded the market, giving hoops away in neighborhoods to create a buzz and required Wham-O executives to bring hoops with them on planes so people would ask about them. Wham-O was soon producing 20,000 hoops a day at plants in at least seven countries while other companies made knock-offs. Within four months, 25 million of the hoops had been sold, according to Wham-O.

In the 1985 book “American Fads,” Richard Johnson wrote that “no sensation has ever swept the country like the Hula Hoop.” The craze also provided a significant business lesson.

“In April of 1958, people were standing around the block at department stores that were waiting to get their shipment,” Knerr’s son, Chuck, told the Los Angeles Times. “By September you couldn’t give them away. Once every household had two or three, it was over because they lasted forever.”

Wham-O toys often had an air of originality that Knerr called the “wow” factor. He defined it as the moment when “you’re … showing it off and everybody says, ‘What’s that? What’s that?'”

The company founders experienced their own “wow” moment when former Air Force pilot Fred Morrison was spotted at the beach playing with his invention, the Pluto Platter. They bought the rights, modified it and renamed it Frisbee before releasing it in 1958.

The name may have come from a comic strip called “Mr. Frisbie” or from the Frisbie Pie Co. tins that reportedly inspired the disk’s invention. Both versions of the story have been attributed to Knerr.

Initially, Frisbees were marketed by word of mouth on college campuses, and more than 100 million Frisbees were sold in 30 years. A professional model went on sale in the 1960s, and the team sport known as ultimate Frisbee was soon played on college campuses. Since 1975, Frisbee Dog World Championships have been held.

“We didn’t want it used as a toy,” Melin told the Pasadena Star-News in 1998. “We wanted it to be a sport.”

In 1982, the founders sold the company for $12 million to Kransco Group Cos. Mattel Inc. bought Wham-O in 1994 and resold it to a group of investors in 1997.

Richard Knerr was born June 30, 1925, in San Gabriel.

As a teenager, he met his future business partner, Melin, and the two remained lifelong friends.

They went to the University of Southern California together, and Knerr earned a bachelor’s degree in business in the late 1940s.

At Wham-O, the duo remained wildly open to ideas.

The approach could result in flops, such as the do-It-yourself fallout shelter, marketed at the height of the Cold War for $119 or the kit with plastic great white shark teeth that came out when the movie “Jaws” did in 1975.

Melin died in 2002.

In addition to his wife Dorothy, whom he married in 1979, Knerr’s survivors include his three children from a first marriage, Melody Knerr, Chuck Knerr and Lori Gregory; two stepchildren, Richard Enright and Jeanne Stokes; and eight grandchildren.