Jim Henson, 53, the puppeteer who created Big Bird, Miss Piggy, Kermit the Frog and the rest of the Muppets and then made them the endearing stars of some of the world's funniest, most instructive and widely admired television programs, died of pneumonia yesterday at a hospital in New York City.

David M. Gelmont, the doctor who treated Henson at New York Hospital, said his patient apparently came down with flu in North Carolina on Friday and was examined by a doctor there who did not find the pneumonia. By the time he was admitted to New York Hospital on Tuesday, the infection had spread throughout his body, causing multiple organ failures.

Henson began the Muppets in the 1950s when he went to work for WRC-TV (Channel 4) in Washington between his graduation from Northwestern High School in Hyattsville and his enrollment at the University of Maryland. The puppets went on to legendary careers as the stars of "Sesame Street," "The Muppet Show" and many other productions. Engaging the hearts and minds of young and old alike, they became a worldwide phenomenon.

"The Muppet Babies" is a highly honored cartoon series on Saturday mornings, and there have been television specials, films, records, toys, T-shirts, dolls and trinkets. The Walt Disney Co., which paid Henson an estimated $100 million last year for the offspring of his imagination, is building a Muppets theme park, thus conferring on them a status equal to that of Donald Duck and Mickey Mouse.

The Henson creations, so abidingly human that it is hard to remember that they are illusions concocted of foam rubber and bits of flannel and wool, remain at the center of all the attention: Oscar the Grouch, who is often out of sorts; the Cookie Monster, who likes cookies (of course) and almost everything else to eat; the mild-mannered Kermit; Big Bird, who is one of the nicest "people" ever; the humanoids Bert and Ernie and Sam the Robot; the Count, a vampire-like creature who is not so scary after all and counts everything; Mr. Snuffleophagus, who is homely but lovable; Miss Piggy, who is loosely modeled on Mae West and who refers to herself as "Moi"; and many others.

They are daily visitors, if not honorary family members, in households everywhere. "Sesame Street" is seen in more than 80 countries and has 15 international coproductions. "The Muppet Show" is said to have attracted more viewers than any other television program in history, having been watched in 100 countries. Parents who grew up watching the Muppets now turn to their programs and gadgets to delight and instruct their own children.

But the appeal of the creatures is hardly limited to children. In the 1950s and 1960s, they appeared frequently on "The Ed Sullivan Show" and "The Jimmy Dean Show," and later on "Saturday Night Live." They have often been on "The Tonight Show" with Johnny Carson. Some of the great names in the entertainment industry, including Danny DeVito, Lena Horne, Placido Domingo and Meryl Streep, have been guests of the Muppets. Some were honored by having Muppets named after them.

"Sesame Street" started on public television in 1969 as a way of helping children aged 1 to 5 learn their numbers and standard English and master such concepts as up and down and near and far. It was directed in particular to inner-city neighborhoods. It was clear immediately, however, that its ability to attract audiences was universal. Parents as well as children have been delighted by such shenanigans as Oscar the Grouch inviting Candace Bergen to dinner and becoming more and more beguiled by her as she rejects each of his proposed menus with a synonym for "revolting."

Henson's other projects included "Teenage Mutant Ninja Turtles," the current box office smash; "The Muppet Movie" (1979); "The Great Muppet Caper" (1981); and "The Muppets Take Manhattan" (1984), in which Kermit married Miss Piggy. He also did a series of television fantasies called "Storyteller." Other television productions include "The Ghost of Faffner Hall" and "Fraggle Rock." In 1986, he did "The Jim Henson Hour," a special on NBC.

He won the highest accolades and great wealth. The honors included two Emmys for "Sesame Street," three for "The Muppet Show," four for "The Muppet Babies" and one for "The Jim Henson Hour," a Peabody Award for excellence in television programming and a Grammy for a Muppets album.

The creator of what one critic called this "theatrical magic" was born on Sept. 24, 1936, in Greenville, Miss., and named James Maury Henson. His father was an agronomist with the U.S. Department of Agriculture. When he was transferred to the Washington area, the family settled in Hyattsville. While attending Northwestern High School, Jim Henson joined a puppet club.

When he graduated in 1954, he went to work for WRC-TV, which was looking for a puppeteer for a show called "Sam and His Friends." It was five minutes long, it used the Muppets (so called, according to Henson, because they were a cross between marionettes and puppets), and it was broadcast just before "The Tonight Show." Henson kept the job while attending Maryland, where he graduated with a degree in fine arts.

"We'd try some really way-out things," he said in an interview. "I was convinced no one else at the station ever watched the show because there was never a complaint or any attempt at censorship of any kind."

In 1958, "Sam and His Friends" won a local Emmy. Henson went to Europe that summer and there he decided to make puppets his career. "In Europe, everybody goes to puppet shows," he said.

After college, he began making television commercials. One of his early characters was Rowlf the Dog, the invention of his colleague Don Sahlin. He also began appearing on network programs, and a New York Times reporter wrote of interviewing a dog named Rowlf. In 1965, Henson wrote, produced, directed and starred in an experimental film called "Timepiece." It was nominated for an Academy Award. He also did a documentary on youth for NBC in 1968 and a drama for the same network in 1969.

His career took off with the advent of "Sesame Street." In the course of time, he set up production studios in New York and London. Most of the filming was done in London. But the characters were created in a studio on the East Side of Manhattan.

Slender, bearded and soft-spoken, Henson was said by colleagues to have presided over his domain with great calm despite "a streak of madness running through him." A partner in all his works was his wife, the former Jane Nebel, whom he met while both were undergraduates at Maryland.

"When you do puppets," Henson told an interviewer, "you can create the whole show yourself: write it, perform it, direct it, design it. Everything. It's a way of saying something, I guess, and a lot of people want to say something. But I don't start out to say things. I try to keep it, first of all, entertaining, and then humorous. Also, puppetry is a good way of hiding."

He said the success of the Muppets might be the result of the fact that he had no preconceptions about puppets when he started.

"Each puppet is designed specifically for television," he said. "They're very simple. I've tried to get away from the mechanical things because I think it's distracting, especially on TV, where everything is concentrated into such a small area.

"Who was it that said, 'The ear is the enemy of the eye'? A painted expression on a doll is okay in a show where the audience is 15 feet away, but on TV you have to put life and sensitivity into a face."

In addition to his wife, of New York City, survivors include five children, Lisa, Cheryl, Brian, John Paul and Heather, all of whom are in show business.

Henson, who provided the voices for Kermit and Ernie, once said that "puppets have the same sort of graceful aging that cartoon characters have. I'm sure Kermit will stay younger a lot longer than I will."