Dave Thomas the founder and well-known pitchman for the Wendy's burger chain died at his home in Florida, the company said Tuesday.

Thomas, 69, died around midnight at his residence. The company said he succumbed to liver cancer after having a tumour for more than a decade.

He had also been receiving dialysis for a kidney problem since early 2001, and underwent quadruple heart bypass surgery in December 1996.

"Dave was our patriarch, a great, big lovable man," Jack Schuessler, chairman and CEO of Wendy's International, said in a statement. "He was the heart and soul of our company."

Founded by Thomas in Columbus, Ohio in 1969, Wendy's Old Fashioned Hamburgers carried the nickname of Thomas' eight-year-old daughter Melinda Lou, who was called Wendy by her siblings.

The burger chain eventually grew to 6,000 restaurants in the United States, Canada and dozens of other countries.

In 1995, the company expanded by buying out a Canadian institution the Tim Hortons donut chain, which now numbers over 2,000 outlets.

In 2000, Wendy's and Tim Hortons had combined sales of $7.7 billion US.

Since 1989, the folksy Thomas featured prominently in the burger chain's television advertising campaigns. He would eventually star in more than 800 commericals.

"Although Dave was widely popular, he was never very comfortable as a celebrity. He kept reminding us he was simply a hamburger cook," Schuessler said. "He was a humble man who was very comfortable in an apron behind a grill or in a business suit in a board room."

Born in Atlantic City, New Jersey in July 1932, Thomas was adopted at six weeks old. In later life, Thomas became an advocate for adoption. He set up the non-profit Dave Thomas Foundation for Adoption to educate people about the cause.

A high school dropout who gave up his eduation at age 15 to work full time in a restaurant, Thomas went back to school 45 years later. His 1993 Fort Launderdale graduating class voted him "Most Likely to Succeed."