The strip, which turned 50 this year, spawned books, animated cartoons, a television series and two movies. It still appears in more than 1,000 newspapers in the United States and 47 other countries.
Fellow cartoonists hailed Ketcham's genius at depicting a slice of American life that has resonated with readers for five decades.
"Dennis," said Mell Lazarus, the creator of the "Momma" strip, "was a brilliant combination of rottenness and charm in one little creature. Hank just nailed him. It just worked, for 50 years. It is in the same position as it was in its heyday. That's quite remarkable."
Others paid tribute to Ketcham's artisty, recalling his dedication to detail, perspective and composition.
"Everybody envied his ability to draw," said Mort Walker, who originated the Beetle Bailey strip. "In the humor field, he was the best artist among us all."
Dennis the comic creation is a somewhat pudgy, often dirt-smudged half-pint with a cowlick and freckles who hates carrots but loves peanut butter and ketchup. Aggressively curious, he was, Ketcham once said, a boy who was "too old for the playpen ... too young for jail."
"It's really Hank Ketcham's fantasy or vision of the ideal childhood," said Brian Walker, Mort's son, who helps produce "Beetle Bailey" and as a cartoon historian curated a retrospective of Dennis' art now on display at the International Museum of Cartoon Art in Boca Raton, Fla.
Ketcham began to draw as a child growing up in Seattle. A seminal moment occurred when he was about 6 and watched an artist friend of his father quickly scribble some of his favorite cartoon characters -- Barney Google, Moon Mullins and Andy Gump.
"I coudn't wait to borrow his "magic pencil' and try my own hand at drawing the comic strip charcters," Ketcham recalled in his 1990 autobiography, "The Merchant of Dennis the Menace."
He began to trace every single comic in the Seattle newspapers and proudly demonstrated his talent for his second-grade classmates. Too skinny to be an athlete and "too dense" by his own description to be an intellectual, he found humor to be the way to get along in school.
He spent only one year at the University of Washington, where he majored in art and minored in drama. After seeing Walt Disney's "The Three Little Pigs" cartoon, he promptly lost his interest in higher education. He hitchhiled to Hollywood with dreams of working for Disney.
His first job, however, was in an ad agency, changing the water for the artists for $12 a week. His next job moved him closer to his dream, working with the legendary animator Walter Lantz at Universal.
Finally, he was hired at Disney, where he assisted on "Pinocchio," "Fantasia" and "Donald Duck" short features.
When the U.S. entered World War II, he enlisted in the Navy but managed to continue his animation work.
He also drew and wrote promotional materials used to sell war bonds.
In 1943 he created "Half-Hitch," a comic about the adventures of a diminutive sailor that became a regular feature in the Saturday Evening Post and boosted Ketcham into the ranks of big-time cartoonists.
By that time he had married his first wife, Alice, who was an admiral's secretary. Their son, Dennis, was born two years after their marriage, in 1946.
The comic-strip Dennis was conceived four years later, on an October afternoon in 1950, when Ketcham was finishing a drawing at his home studio in Carmel, Calif. The Ketchams' son was supposed to be resting but instead had spent his naptime quietly dismantling his room -- the bed, mattress, springs, dresser, drapes and curtain rods.
"When the accidental load he carried in his underpants was added to his collection of plastic toys, cookie crumbs and a leftover peanut buter sandwich, it formed an unsuual mix," Ketcham wrote in his autobiography. "Enough to drive an Irish mother to the brink." Alice Ketcham stormed into his studio, fuming "Your son," she declared, "is a menace!"
Ketcham responded by pulling out a shoebox where he stored his gags. He culled out the "kid ideas" and feverishly began to sketch. He air-mailed the drawings to his agent, who 10 days later telegrammed him with good news: Send more drawings, a syndicate is interested.
The first "Dennis" comic made its debut in 15 newspapers a few days before Ketcham's 31st birthday, on March 12, 1951. Within a few years it had spread to 193 papers in the United States and 52 papers abroad.
There were Dennis dolls, aprons, cookie jars, clothes. It even inspired a record by Rosemary Clooney and was used by psychologists at Columbia University's Teachers College in lessons on how to use humor to handle children.
Mail poured in by the bushel from readers who told him he must have been spying through their window. "Our little boy," went a typical letter, "does just the same things Dennis does."
Ketcham's family life during his first marriage lacked the happy endings of his strips. He separated from Dennis' mother, who died soon after in 1959 from a drug overdose. Ketcham took his then 12-year-old son to live in Switzerland but the boy did poorly there and was sent to boarding school in Connecticut. Ketcham remarried and remained in Europe.
Dennis Ketcham served a tour of duty in Vietnam as a marine, but returned suffering from post-traumatic stress syndrome and drifted from job to job. As an adult, he had little contact with his father and once blamed the failure of their relationship on how much cartooning occupied his time.
Ketcham, who once described himself as "more like Mr. Wilson," the grumpy neighbor, returned to California as a multi-millionaire in 1977, in part because he was losing touch with American culture after nearly two decades abroad.
Divorced and married a third time Ketcham is survived, in addition to Dennis, by his third wife, Rolande, and two other children, Scott and Dania.