In popularity, Mr. Neiman rivaled American favorites like Norman Rockwell, Grandma Moses and Andrew Wyeth. A prolific one-man industry, he generated hundreds of paintings, drawings, watercolors, limited-edition serigraph prints and coffee-table books yearly, earning gross annual revenue in the tens of millions of dollars. Although he exhibited constantly and his work was included in the collections of dozens of museums around the world, critical respect eluded him. Mainstream art critics either ignored him completely or, if forced to consider his work, dismissed it with contempt as garish and superficial — magazine illustration with pretensions. Mr. Neiman professed not to care.

Maybe the critics are right,” he told American Artist magazine in 1995. “But what am I supposed to do about it — stop painting, change my work completely? I go back into the studio, and there I am at the easel again. I enjoy what I’m doing and feel good working. Other thoughts are just crowded out.”

His image suggested an artist well beyond the reach of criticism. A dandy and bon vivant, he cut an arresting figure with his luxuriant ear-to-ear mustache, white suits, flashy hats and Cuban cigars. “He quite intentionally invented himself as a flamboyant artist not unlike Salvador Dalí, in much the same way that I became Mr. Playboy in the late ’50s,” Hugh Hefner told Cigar Aficionado magazine in 1995.

LeRoy Runquist was born on June 8, 1921, in St. Paul. His father, a railroad worker, deserted the family when LeRoy was quite young, and the boy took the surname of his stepfather.

He showed a flair for art at an early age. While attending a local Roman Catholic school, he impressed schoolmates by drawing ink tattoos on their arms during recess.

As a teenager, he earned money doing illustrations for local grocery stores. “I’d sketch a turkey, a cow, a fish, with the prices,” he told Cigar Aficionado. “And then I had the good sense to draw the guy who owned the store. This gave me tremendous power as a kid.”

After being drafted into the Army in 1942, he served as a cook in the European theater but in his spare time painted risqué murals on the walls of kitchens and mess halls. The Army’s Special Services Division, recognizing his talent, put him to work painting stage sets for Red Cross shows when he was stationed in Germany after the war.

On leaving the military, he studied briefly at the St. Paul School of Art (now the Minnesota Museum of American Art) before enrolling in the School of the Art Institute of Chicago, where, after four years of study, he taught figure drawing and fashion illustration throughout the 1950s.

When the janitor of the apartment building next door to his threw out half-empty cans of enamel house paint, Mr. Neiman found his métier. Experimenting with the new medium, he embraced a rapid style of applying paint to canvas imposed by the free-flowing quality of the house paint.

While doing freelance fashion illustration for the Carson Pirie Scott department store in Chicago in the early 1950s, he became friendly with Mr. Hefner, a copywriter there who was on the verge of publishing the first issue of a men’s magazine.

In 1954, after five issues of Playboy had appeared, Mr. Neiman ran into Mr. Hefner and invited him to his apartment to see his paintings of boxers, strip clubs and restaurants. Mr. Hefner, impressed, showed the work to Playboy’s art director, Art Paul, who commissioned an illustration for “Black Country,” a story by Charles Beaumont about a jazz musician.