Inventor, TV pitchman and salesman extraordinaire Ron Popeil became a familiar presence in America’s homes and imaginations by demonstrating products he persuaded viewers they couldn’t live without: the Veg-O-Matic, the Pocket Fisherman, spray-on hair, and especially the Showtime Rotisserie and BBQ countertop oven.

“Isn’t that amazing?” he would say, first as a street hawker and store demonstrator and later in late-night TV commercials and half-hour infomercials, which he helped develop into a hybrid form of entertainment and commerce.

“You can slice a tomato so thin it only has one side!” he exclaimed about his Six Star Plus knives, which stayed sharp after cutting through shoe leather and pieces of wood. “Now how much would you pay?” he would say.

Mr. Popeil (pronounced poh-PEEL), whose Ronco brand of products became staples of postwar households and who infused pop culture with phrases such as “No muss, no fuss,” “But wait, there’s more” and “Set it and forget it,” died July 28 at a Los Angeles hospital. He was 86.

The death was confirmed by a spokesman, Eric Ortner, who said he had a “sudden medical emergency” but did not cite a specific cause.

His products were mocked for being cheap and poorly made, and Mr. Popeil was the subject of mockery himself — most memorably by Dan Aykroyd on a 1976 episode of “Saturday Night Live,” when he dropped a whole fish into a “Bass-O-Matic” and blended it into a piscine smoothie.

Mr. Popeil took the humor in stride, played along with talk-show hosts and saw any kind of publicity as free advertising for his products. He began as a teenage salesman, setting up a stand on a sidewalk flea market in Chicago, where he sold kitchen gadgets — the Chop-O-Matic and Veg-O-Matic, among them — invented by his father.

“I saw all these people selling products, pocketing money, making sales, and my mind went racing,” Mr. Popeil said in a 1995 autobiography, “The Salesman of the Century,” written with Jefferson Graham. “I can do what they’re doing, I thought. But I can do it better than they can.”

Each morning, he bought 50 pounds of onions, carrots and cabbages as well as 100 pounds of potatoes and, by the end of a 12-hour day, had sliced and diced through all of them, keeping up a steady patter all the while.

“Ladies and gentlemen, I am going to show you the greatest kitchen appliance ever made,” he would say. Then: “All your onions chopped to perfection without shedding a single tear.”

Mr. Popeil was 16 when a Chicago newspaper called him “a silver-tongued orator.” Two years later, he was demonstrating products at a Woolworth’s store, sometimes clearing as much as $1,000 a week.

“He was mesmerizing,” Mel Korey, who later became a business partner, told the New Yorker in 2000. “There were secretaries who would take their lunch break at Woolworth’s to watch him because he was so good-looking.”

He knew just when to start asking onlookers to reach for their wallets — what street sellers call “the turn.” But before he sold to everyone, thus dispersing the crowd, Mr. Popeil would say, “But wait, there’s more,” drawing even more people to his spiel.

He was soon traveling to state fairs around the country, and in 1956 he made his first television commercial, a 3½-minute spot for the Chop-O-Matic, which some observers have called one of the first infomercials.

In 1964, Mr. Popeil and Korey started Ronco, taking advantage of television advertising. Mr. Popeil refined some of the items developed by his father and uncles, who were in the same business, and began to invent his own.

Over the next few years, he began to market the Smokeless Ashtray, Popeil’s Pocket Fisherman (a miniature fishing rod and reel), Inside-the-Shell Egg Scrambler, Popeil’s Pasta & Sausage Maker, and the Buttoneer (“The problem with buttons is they always fall off.”).

He invented Popeil’s Electric Food Dehydrator for making banana chips, dried apples and beef jerky — “I love beef jerky, but you can’t find good homemade beef jerky,” he said by way of explanation. He sold more than $100 million worth of the machine in two years.

His GLH Formula Number 9 Hair System — often called hair in a can — covered bald spots with a powder that could be combed into the surrounding hair. (Mr. Popeil gladly turned around to show his own bald spot to demonstrate how it worked.)

“People always ask me, ‘Ron, where did you get that name GLH?’ ” he told the New Yorker. “I made it up. Great-Looking-Hair.”

A few of his products were available in stores, but most were sold by direct mail from low-budget TV commercials that featured Mr. Popeil demonstrating how the items worked. He bought as much as $1 million in advertising a week and became a familiar figure on late-night programming.

Following the lead of K-Tel, a company developed by Canadian pitchman Phil Kives, Ronco sold millions of compilation recordings of classical music, disco, soul and military music in the 1970s and 1980s.

In every commercial, Mr. Popeil had what he called the “countdown,” telling his viewers how much a bargain they were getting by quoting absurd prices that they wouldn’t pay.

“Remember, folks, if you call now,” he said, selling a set of knives, “you’ll receive over $840 worth of the finest stainless steel cutlery that money can buy.” But “all you spend right now is only three easy monthly payments of just $13.33.”

A millionaire many times over, Mr. Popeil lived in Beverly Hills but dined at Denny’s and shopped at Costco. During one of his Costco visits, he saw crowds lined up to buy rotisserie-roasted chicken.

Mr. Popeil got to work. He bought an aquarium, an electric motor, a heating element, a metal spit rod and a few other spare parts and began to tinker. He and one of his assistants, Alan Backus, worked on several different models, which they tested in Mr. Popeil’s kitchen, cooking chicken, duck and pork.

Mr. Popeil wanted the front of the oven to be glass to enable people to see the food as it roasted. The spit had two prongs and had to rotate horizontally, not vertically, to cook evenly and not dry out. He tested the durability of the cooker by dropping it on concrete 10 times.

Finally, the Showtime Rotisserie and BBQ countertop oven was ready. Mr. Popeil made a half-hour infomercial that first aired in 1998, and sales rocketed. Demonstrating how easy the cooker was to use, he uttered a phrase that studio audiences later chanted in unison with him: “Set it and forget it.”

Sales of the Showtime Rotisserie totaled more than $1 billion, making it by far the most successful Ronco product. Mr. Popeil developed the oven without focus groups, a marketing campaign or research staff, except for the friends who ate his chicken and helped him tinker with the electronic innards of the machine.

“My forte is mass marketing for big dollars,” he told the Boston Globe. “The product has to fill a need and the market has to be very big.”

Ronald Martin Popeil was born May 3, 1935, in New York City. He was 3 when his parents divorced, and his father largely abandoned him. He spent several years at a boarding school before he was taken in by his strict grandparents in Florida. (In 1974, Mr. Popeil’s stepmother was convicted of hiring hit men to kill her estranged husband. She served 19 months in prison, and the two later remarried.)

One of the reasons he enjoyed selling directly to people on the street or in department stores, he told “CBS Sunday Morning” in 2000, was that “I had lived for 16 years in homes without love. Now I had finally found a form of affection, and a human connection, through sales.”

He admitted in his autobiography that he was a compulsive workaholic who had been an inattentive husband and father. Survivors include his fourth wife, the former Robin Angers; four daughters; and four grandchildren.

In 1984, Mr. Popeil’s Ronco empire nearly collapsed, but he bought the rights to his products and rebuilt the company. He sold it in 2005 but continued inventing new products until shortly before his death.

“I have enough money today,” he said in 1997, “but I can’t stop. If there’s a need for these things, I can’t help myself.”