Although he resembled an Old Testament prophet, Al Hirschfeld, who has died aged 99, was more entertaining than any Ezekiel: he caught Broadway in its golden age, and beyond, benignly unsparing in his observation. Over some eight decades, the orderly extravagance of his caricatures took Paul Klee's pronouncement at its word - "a line is a dot out for a walk".
Hirschfeld was born in St Louis, the son of a tailor who did not speak either of his wife's languages - Russian and Yiddish - when they first met. "All children draw, I just never stopped," said Hirschfeld. His talent was such that his parents agreed when a teacher told them that they had to move to New York when the boy was 12 to advance his development. There, his mother worked in department stores while his father looked after the family. Hirschfeld was mesmerised by vaudeville and burlesque shows but, although certain of his talent, he did not know what part the stage would play in his career.
He began as a sculptor ("sculpture is a drawing you fall over by the door"), but also tried watercolours and oils before finding a job at Goldwyn Pictures by accident - "like everything in life". By 20 he was an art director at Selznick Pictures, producing posters, but he fell into debt and paid it off working at Warners. This so impressed an uncle that he sent the young man to Europe with $500. He lived cheaply in Paris in a cold-water flat and, of course, grew a beard.
Back in New York in 1926, he made a sketch at a show starring Sacha Guitry. It was admired by the press agent with him, who sold it to the Tribune. "That was it, never occurred to me I'd still be making a living at it," he said almost 70 years later. He soon acquired the barber's chair in which he always worked, and sometimes attributed his expansive style to "a Machiavellian scheme for paying the rent": his work spread across pages - and he was paid by the column inch.
At one period he was more than interested in radical politics, and spent a year in Russia. He learned "that's not my field, but people and customs and manners."
The New York Times wanted first crack at his work. He said: "Cross my palm with silver and I'm your fellow." Only in the mid-1990s was anything so formal as a contract with the paper signed.
He married showgirl Flo Allen, and in 1931 they went to Tahiti for two months ("a very romantic adventure which broke up our marriage"). The place was "a corrupt rum-running port. Horrible, food was awful, natives syphilitic." They went on to Bali, which, with its strong light, was perfect for black line, and was crucial to his evolving style. There he began properly to appreciate such artists as Hokusai and Utamaro, whose work he had known since adolescence.
After a year, he was broke; Charlie Chaplin chanced by and bought some watercolours, and so Hirschfeld was able to return to New York. There he shared a studio with the Mexican artist Miguel Covarrubias, as great an influence on him as Beardsley and Beerbohm. He went to rehearsals and out of town try-outs, making notes and sketches from which to work back home.
In 1935 he met the actress Dolly Hass, who had been famous in Germany before the rise of Marlene Dietrich. She told him that she liked a drawing she had seen. "I did it," he replied. They married (she died in 1994) and she was vital to his work, fending off people, commenting on work in progress (which could take hours or days). "She straightened me out every now and then. I listened to her very carefully." Such was her organisational legacy that after her death he was able to continue working as before.
He crested on the great wave of 1940s and 1950s musicals, although he admitted he had seen no future for Oklahoma! until Oh, What A Beautiful Morning! was introduced as the opening number. He also told Moss Hart that there was no room for another version of Pygmalion - not even the one that became My Fair Lady.
Once in a while somebody, usually not a star, was offended, but few leading performers were outraged by the outlandish necks and baroque hairstyles he gave them. Though Kitty Carlisle Hart may have said that "caricature is one thing but this abused the privilege", Carol Channing thought "It's not unflattering really - I'd like to look like that." Katharine Hepburn said "I think I'm rather easier than some - I've got exaggerated nostrils, the mouth goes down, the cheeks go hollow." In his 1970 book, The World Of Hirschfeld, he wrote: "My contribution is to take the character, created by the playwright and acted out by the actor, and reinvent it for the reader." About the most malicious he got was to draw David Merrick, the producer, as a nasty Santa Claus figure: Merrick bought the image for his Christmas cards.
Hirschfeld liked "people who've invented themselves, they're like exploded ventricles." He was no standard-issue human. "I was fascinated when I met him," said Hepburn, "because his whole body has all the spring and the delight and the elasticity that his drawings have."
She was one of many to marvel that he never took any exercise other than walking up and down the staircase of his house; and she boggled at his driving technique. Even in his 90s he was granted a new driving licence, despite not being able to see the wall chart, or so he claimed.
In the 1940s he had collaborated with his friend SJ Perelman on a musical called Sweet Bye And Bye, the opening night of which, in Philadelphia, was also its final performance. "We had to leave the country after that," said Hirschfeld. With a commission from Holiday magazine, he and Perelman travelled the world for nine months to recover, producing their book, Westward Ha! or Around The World In 80 Clichés. It made Hirschfeld enough to buy his Manhattan townhouse. He also worked on another SJ effort, Swiss Family Perelman. Among his own books were Hirschfeld On Line (1999) and works on New York and Hollywood, published in connection with museum exhibitions.
He produced some 12,000 drawings, attributing this output to a determination "not to get stale, bored or mentally constipated", from the era of Rodgers and Hammerstein through Hair and Tommy to Bring On Da Noise, Bring On Da Funk. His flowing lines influenced the hundreds of animators who created the Disney Aladdin.
After 1945 there was always a number next to his signature: a tally of the times that he had worked the name of his daughter Nina into the drawing, into perhaps a beard or a necklace - they could pop up anywhere. Finding Nina each week had such a following that he could not drop the game, and Nina came to feel that the strange fame hindered her life. The Pentagon paid a professor to develop a programme that made Nina-spotting part of the bomb-aiming training of pilots. The US Postal Service waived its policy forbidding secret marks and allowed her tiny name on five stamps depicting comedians which were designed by Hirschfeld in 1991.
He remarked that "the whole trick in art is to stay alive" and "life is an art not a science, you make it up as you go along." He improvised with bravura; to browse through his albums is to be invigorated by that energy which Jules Feiffer once called the graphic equivalent of Fred Astaire's dancing.
In 1996, he married Louise Kerz, theatre historian and widow of a producer and set designer; the couple became a familiar sight at theatre openings. She noted that his work "is often more revealing than a camera, because of the drawing's flair and fluidity of movement".
Just before he died, the American Academy of Arts and Letters told him he had been elected to membership, and he was about to be presented with the National Medal of Arts. In June, the Martin Beck Theater on West 45th Street, New York, will be renamed the Al Hirschfeld Theater.
His wife and Nina survive him.
· Albert Hirschfeld, caricaturist, born June 21 1903; died January 20 2003