Dave Thomas, 69, the jowly and bespectacled founder of the Wendy's restaurant chain whose avuncular presence in hundreds of television commercials since 1989 made him one of the country's most recognized corporate figures, died of liver cancer Jan. 8 at his home in Fort Lauderdale, Fla., company officials said.

Mr. Thomas, a high school dropout with a troubled childhood, got his first job pumping gas when he was 10, started his food career delivering groceries when he was 12 and later transformed Wendy's Old Fashioned Hamburgers from a single restaurant that opened in Columbus, Ohio, in 1969 into an international fast-food concern with more than 6,000 outlets.

Wendy's merged with the Canadian chain Tim Hortons in 1995. Together, the two chains have annual sales exceeding $8 billion.

That his was a textbook case of an idealized American Dream was not lost on Mr. Thomas, who wrote and spoke widely on the subject, preaching such platitudes as "mop bucket attitude," his own version of an MBA program.

Mr. Thomas, who was associated with conservative political causes, also used his personal story and celebrity to further adoption programs. In 1990, he headed the White House Initiative on Adoption. The Dave Thomas Foundation for Adoption was founded in 1992, with a close relationship to Wendy's.

In 1996, Mr. Thomas was credited by President Bill Clinton with helping to win passage of legislation that gives adoptive parents a one-time tax credit of $5,000. He also was credited with promoting 1997 legislation that sought to speed the adoption process.

R. David Thomas was born in Atlantic City. He never knew his birth parents and was adopted at 6 months old by a Kalamazoo, Mich., couple. His adoptive mother died when he was 5, and he and his father, a carpenter and tradesman, moved from town to town. In his 1991 memoir "Dave's Way," he wrote, "I never remember him hugging me or showing any affection."

Mr. Thomas got his first restaurant job at age 12 at a Walgreens in Knoxville, Tenn. When he was 15, he became a busboy at the Hobby House Restaurant in Fort Wayne, Ind. Unhappy at home, he dropped out of high school (what he called his greatest mistake) and moved into the local YMCA.

After serving a stint in the Army, where he was a manager for enlisted men's clubs, he returned to Fort Wayne and was promoted to manager at the Hobby House. There he met two important people in his life. The first was a waitress, the former Lorraine Buskirk, who would become his wife.

The second was the legendary Harland Sanders, "The Colonel" of Kentucky Fried Chicken fame, who made a stop at the restaurant hawking chicken products. He and Sanders struck up a friendship, and Mr. Thomas afterward would often cite Sanders's influence on his career and marketing strategies.

In 1962, Mr. Thomas was offered a share in four failing Kentucky Fried Chicken restaurants in Columbus. He turned them around, sold his stake and used the profits to open his own restaurant.

Mr. Thomas named it "Wendy's" after his second-youngest daughter, Melinda (her younger brother and sister could only pronounce "Wenda"). Mr. Thomas put her hair in pigtails and took her to a sign painter, and the now-familiar Wendy's logo was born.

Mr. Thomas began franchising the restaurant in 1972, and the chain, capitalizing on consumers looking for alternatives to McDonald's, took off, at one point opening 1,000 stores in 100 months.

Overextended after the success of the popular "Where's the beef?" campaign, Wendy's was looking for another successful pitch when, in 1989, as he was explaining Wendy's cooking procedures to an advertising executive, Mr. Thomas was asked whether he would like to hawk the product himself.

In his memoir, Mr. Thomas said he was reluctant, because "I have a hard time saying my name, let alone anything else, but I told him, 'I'll try, but if it doesn't work now or if it ever stops working, I'm history.' "

The early reviews were poor, with critics deriding Mr. Thomas's bad English and midwestern locution and even his appearance. Advertising Age's Bob Garfield said he looked like a "steer in a half-sleeve shirt."

However, the commercials, most of them employing deadpan humor, were a hit with consumers and raised Wendy's profile and profits, with marketers carefully crafting the homespun edge.

Garfield later recanted and in an interview yesterday called Mr. Thomas "one of the most beloved and successful product presenters in the history of advertising."

"He just had a charisma and folksy appeal that transcended his own limitations as an actor," Garfield said. "More importantly, he was a perfect match for his brand. Wendy's hamburgers are square and old-fashioned. Dave Thomas was square and old-fashioned."

Mr. Thomas appeared in the commercials with a white shirt and red tie and sometimes wearing an apron. In a typical spot, he appeared in a fancy restaurant, shaking his head at the froufrou atmosphere, and later at a Wendy's biting happily into one of his own sandwiches.

It wasn't only on style that Mr. Thomas's commercials were criticized. Over the years, consumer groups have questioned several of his claims, including whether Wendy's hamburgers were actually prepared-to-order, whether they weighed as much as advertised and whether certain foods implied to be vegetarian actually contained animal fat.

Regretting his decision to drop out of high school, Mr. Thomas returned to complete his diploma in 1993 at Coconut Creek High School in southern Florida. He and his wife were voted the king and queen of the high school's prom, and, upon completing his degree, Mr. Thomas was voted by classmates as "Most Likely to Succeed."

Among Mr. Thomas's many honors was the 1979 Horatio Alger Award, presented to him by one of his heroes, Norman Vincent Peale.

Survivors include his wife; five children; and 16 grandchildren.

Dave Thomas's success was a textbook case of an idealized American Dream, but Thomas always considered himself "just a hamburger cook."