The cause was cancer, said his brother, Thomas.
Mr. Cullum, a TWA pilot for more than 30 years, was a classic gag cartoonist whose visual absurdities were underlined, in most cases, by a caption reeled in from deep left field. “I love the convenience, but the roaming charges are killing me,” a buffalo says, holding a cellphone up to its ear. “Your red and white blood cells are normal,” a doctor tells his patient. “I’m worried about your rosé cells.”
Mr. Cullum seemed to have a particular affinity for the animal kingdom. His comic sympathies extended well beyond dogs, cats and mice to embrace birds — “When I first met your mother, she was bathed in moonlight,” a father owl tells his children — and even extended to the humbler representatives of the fish family. “Some will love you, son, and some will hate you,” an anchovy tells his child. “It’s always been that way with anchovies.”
“There are many ways for a cartoon to be great, not the least of which is to be funny, and Leo was one of the most consistently funny cartoonists we ever had,” said Robert Mankoff, the cartoon editor of The New Yorker. “He was certainly one of the most popular — some of his cartoons were reprinted thousands of times.”
We used to have the New Yorker in the house where I lived in Washington DC. The cartoons were always read first.