At its peak, "Channel Chuckles" was syndicated in more than 200 papers before Keane retired the strip in 1976.
Two years later, he started drawing the comic that was originally called "The Family Circle." When the magazine of the same name objected, Keane changed the second word to "Circus."
For decades, his youngest son, Jeff, has worked with Keane on "The Family Circus" and will continue the cartoon. Another son, Glen, is an animator best known for his work at Disney.
Keane created three animated specials for television and published more than 40 books. In 1971, he collaborated with his neighbor, family-humor columnist Erma Bombeck, on "Just Wait Till You Have Children of Your Own!"
In the foreward to another Keane book, Bombeck wrote: "Mostly I admire and respect Bil's gentleness, his warmth, his respect for that battered, floundering, much-maligned institution — the American family."
Among fellow cartoonists, Keane was known to display a hard-edged sense of humor that Lazarus described as "sardonic." Keane softened his approach for the comic strip, aided by a "tremendous memory" that made it easy to come up with ideas, he later said, and perhaps to continue to see the world through the eyes of a child.
In one panel of "The Family Circus," Jeffy holds a snapshot of his father as a boy and asks, "Mommy, when did Daddy get little?"
Keane is survived by his five children, Gayle, Neal, Glen, Christopher and Jeff; nine grandchildren and one great-grandchild.