Mort Drucker, an artist who created memorable, incisive caricatures of politicians and entertainers, giving a satirical twist to the day-to-day madness of the world as a longtime illustrator for Mad magazine, died April 9 at his home in Woodbury, N.Y. He was 91.

His daughter Laurie Bachner confirmed the death but said she did not know the precise cause.

Mr. Drucker was a largely self-taught artist who joined Mad magazine in 1956 — four years after its founding — and helped make it one of the most subversively influential publications of the 1960s and 1970s.

He was part of a staff of artists, including Jack Davis and Al Jaffee, whose humorous drawings of presidents, film stars and the magazine’s gaptoothed mascot, Alfred E. Neuman — “What, me worry?” — were an irreverent blend of parody, ridicule and affection.

“He had just a supernatural ability to capture the likenesses of political leaders, Hollywood stars and cultural figures,” critic and historian David Apatoff said in an interview. “He was the centerpiece for that magazine. He was the glue that kept it together.”

Mad magazine brought a sardonic brand of humor to its pages, with snarky articles accompanied by elaborate caricatures and portraiture drawn by Mr. Drucker and other artists. Generally published eight times a year during its heyday, Mad reached a peak circulation of 2.8 million in the early 1970s and was eagerly sought out by youthful, iconoclastic readers.

In 1997, Washington Post writer and magazine columnist Peter Carlson called Mad “the most influential American magazine of the postwar era.”

The mischief-making magazine, which ended its print publication last year, was a formative influence on countless comedy writers, satirists, filmmakers and artists. Over the years, its sensibility filtered into such diverse artistic formats as the late-night TV commentary of Jon Stewart and Stephen Colbert, the sketches of “Saturday Night Live,” the musical parodies of Weird Al Yankovic, publications including National Lampoon, Spy and the Onion and the routines of countless standup comedians.

Before he joined Mad, Mr. Drucker had little experience drawing caricatures, but he quickly learned on the job.

“When I started working for Mad,” he told the New York Times in 2000, “they assigned me TV satires and asked me to draw famous people. So I just did it. It took me a long time to learn the skills that I have, and it was time-consuming. With me, everything is trial and error.”

His parodies, drawn with detailed backgrounds and packed with visual puns, viewed the entertainment world through a skewed lens, with the names of celebrities twisted slightly off kilter. The John Wayne western “True Grit” was spoofed as “True Fat”; “Law & Order” devolved into “Law & Disorder”; “The West Wing” became “The Worst Wing”; and “The Godfather” — Mr. Drucker spoofed all three of Francis Ford Coppola’s movies — came out as “The Oddfather.”

“What a fantastic makeup job they did on Marlin Brandow! How did they ever get him to look so old?” one figure asks in Mr. Drucker’s illustration of the title “Godfather” character played by Marlon Brando.

“Very simple! They made him watch his last four movies, and he aged 20 years!”

Movie studios often threatened to sue Mad for its parodies. A 1980 spoof of “The Empire Strikes Back” — portrayed by Mr. Drucker as “The Empire Throws Up” — prompted a nasty letter from lawyers representing director George Lucas. They demanded all profits from that issue of the magazine and asked that the original art be turned over or destroyed.

Publisher William Gaines sent them a copy of a letter received days before from Lucas, in which he gushed about the Mad parody and praised Mr. Drucker as the “Leonardo da Vinci of comic satire.”

“That’s funny,” Gaines wrote on his letter to the lawyers. “George liked it.”

Apatoff, who is the art critic for the Saturday Evening Post and has written often about illustrators, said Mr. Drucker followed in the tradition of Norman Rockwell, whose gentle depictions of domestic life helped define the ethos of mid-20th-century America.

“The parallel is very exact,” he said. “Just like Rockwell was the centerpiece of the Saturday Evening Post, Drucker did the same thing for Mad magazine with his parodies. They were kind of looking at each other through a mirror. The Saturday Evening Post was the height of middle-class domesticity and life in Middle America. Mad made fun of that kind of life. These guys played a significant transformative role in American culture.”

Morris Drucker was born March 22, 1929, in Hurley, N.Y., and grew up in Brooklyn. His father was a plumber and businessman, his mother a homemaker.

Mr. Drucker, who was called “Mort” from an early age, was drawing by the time he entered school. He took a pencil and notebook with him everywhere and, by his teens, was taking classes at New York’s Parsons School of Design.

Once when he ran out of paper at home, his daughters said, he took down the shades in the living room and drew on them. When he put them back, he placed the drawings facing outward toward the street. Neighbors began to complain when they saw racy images of scantily clad women, which the young Mr. Drucker had copied from a calendar.

He often sketched the faces and hands of people riding the subway. His daughters said he would note how a coat draped across a body when someone was standing up and holding an overhead subway bar or strap.

Mr. Drucker began working for DC Comics as an illustrator in the late 1940s. When he took his portfolio to Mad in 1956, according to an often-told story, he was told by publisher Gaines that he could have the job if the Brooklyn Dodgers won their baseball game that day. Fortunately for Mr. Drucker, the Dodgers won.

He stayed at Mad for 55 years, always working from his home studio on Long Island. He occasionally drew for various comic strips on the side and illustrated a coloring book about President John F. Kennedy that sold millions of copies in the early 1960s. He had a syndicated comic strip, about a presidential aide named “Benchley,” for a few years in the 1980s.

He also drew illustrations for advertising and for Time magazines covers, including one from 1971 depicting President Richard M. Nixon playing ping-pong with Chinese leader Mao Zedong. Many of the Time covers are now in the collection of the National Portrait Gallery in Washington.

Mr. Drucker was named outstanding cartoonist of the year in 1988 by the National Cartoonists Society, which gave him its first lifetime achievement award in 2014.

Survivors include his wife of 71 years, the former Barbara Hellerman of Woodbury; two daughters, Laurie Bachner of Manhattan and Melanie Drucker Amsterdam, an illustrator, of Livingston, N.J.; and three grandchildren.

Apatoff called Mr. Drucker one of the “three great caricaturists of the 20th century,” along with Al Hirschfeld, who depicted Broadway for the New York Times and other publications, and David Levine of the New York Review of Books.

When asked what made his work stand out, Mr. Drucker told the Newark Star-Ledger in 2012:

“We all have the same features — eyes, nose, mouth. The question is: Why does one person look different from another? You examine the features. Is the head an oval? Is it rectangular? Then you look at the features within. Are the eyes close to the bridge of the nose? Are they wide-set? It’s all in the proportions of the features.

“That’s how I do it.”