Richard Avedon, who during a career spanning more than 50 years was renowned both for his stripped-down black-and-white portrait photography and his playful yet sophisticated fashion shots, died today.

Avedon, who was 81, died at Methodist Hospital in San Antonio, Texas, of a blood clot in the brain, according to his son, John.

Avedon had been on assignment in Texas for New Yorker magazine, completing a project called "Democracy," a portfolio about politics in America. David Remnick, editor of the magazine, said he plans to publish the work before the Nov. 2 presidential election.

As a fashion photographer, Avedon was among the first to replace the statuesque poses of the past with vivacious action scenes that commanded the pages of Harper's Bazaar and Vogue magazines from the mid-'40s through the 1980s. His models nuzzled elephants in Egypt, hugged sweaty cyclists on the Champs-Elysee in Paris and leaped like gymnasts through his New York City studio.

But increasingly he preferred making portraits of public figures, capturing their inner worlds rather than romanticizing their lifestyles. By eschewing soft lights and cluttered props, he took a stark, often harsh look at his subjects. Many of the photographs taken later in his life were done for the New Yorker, which ran his portraits of people in the arts and politics as a weekly feature starting in 1992.

"Avedon gave us the pared-down study of the famous person, a stripped-away look at their humanity," said Arthur Ollman, director of the Museum of Photographic Arts in San Diego, in an interview earlier this year with The Times. "It is portraiture as interrogation."

Actors, presidents, writers and social activists stood against a blank white background "as if he had pinned them to a wall like a specimen," Ollman said of Avedon's style.

The results could be cold and critical. And yet, said Ollman, "being photographed by Avedon meant you'd made it."

Marilyn Monroe, dressed in sequins and diamonds, appeared to be a bit frightened before Avedon's camera. President Ford squinted warily in a 1976 portrait that suggested an honest if uninspired CEO. Playwright Samuel Beckett, facial lines as deep as tractor tracks, gazed into the camera, seemingly at peace with his demons.

Avedon's eye-to-eye stance regarding his subjects was sometimes compared to German photographer August Sander, who, as the Nazis were rising to power, documented farmers, preachers and others as if they were endangered species.

Avedon once described what he saw in many of the famous faces he photographed.

"People — running from unhappiness, hiding in power — are locked within their reputations, ambitions, beliefs," he wrote in "An Autobiography, Richard Avedon" about his portraits of such tenacious survivors as Kennedy family matriarch Rose Kennedy, writer Truman Capote and pianist/raconteur Oscar Levant.

Other images in the book — of war victims and mental patients — spoke to a different kind of portrait.

"People, unprotected by their roles, become isolated in beauty and intellect and illness and confusion," he wrote.

Avedon found his means of artistic expression early and was among the first to adapt it to larger-than-life-sized portraits — 4 by 6 feet images in the late 1950s, 10 by 30 feet or more in the '60s.

"In art, the monumental size generally had been reserved for gods and presidents," Robert Sobieszek, curator of photography at the Los Angeles County Museum of Art, said today. "Avedon applied it to everyone, from Andy Warhol to ordinary workers in the American West. What he pulled off was the democratization of the photographic image."

Avedon was attracted to stylish rebels. College student Julian Bond and other civil rights activists stood in formation like an army before Avedon's camera; Warhol and his entourage ambled across a three-panel mural; the bearded, bell-bottomed "Chicago Seven" antiwar activists — including Abbie Hoffman, Jerry Rubin and Tom Hayden — bore looks of surprise.

"Avedon's photographs are unrivaled as documents of our time," said Mia Fineman, research associate of the photography department of New York's Metropolitan Museum of Art. "He created an encyclopedia of the key players in the counterculture, the intellectual culture, politics and the arts."

Throughout most of his career, his fascination with street photography and news shots edged its way into his fashion work. For a 1962 layout that ran in Harper's Bazaar, he set up a tabloid news series using Mike Nichols, then a comic and now a film director, and supermodel Suzy Parker as subjects. The glamour couple dashed from a Paris fashion show to a black-tie gala and finally to the American Hospital of Paris. A second look at Parker's wrists revealed they were bandaged, to suggest a suicide attempt.