"He died this morning following a long illness," a friend and colleague told AFP on Saturday.
Such was the appeal of Moebius -- or Jean Henri Gaston Giraud -- that he won a devoted following as far afield as Japan and the United States, countries working in radically different comic-book traditions.
"The whole profession is in shock, totally devastated, even if we knew that he was seriously ill," Gilles Ratier, head of France's Association of Comic-Book Critics, told AFP.
Colleagues paid tribute to the artist and writer generally acknowledged as having been one of the most daring and innovative in his field.
Giraud, who grew up drawing cowboys and indians, published his first drawings in 1957 and found fame with the western character Lieutenant Blueberry in 1963.
The lean, mean gunslinger was to become one of the most iconic figures in French comic-book history.
He adopted the pseudonym Moebius for his illustrations in science fiction books and magazines.
But he also worked under other pseudonyms, including Gir, Giraud and Moeb.
But as Moebius, he said, he operated on a whole different level.
"When I am in the skin of Moebius, I draw in a state of trance, I try to escape from my 'ego'," he told AFP in 2010.
In 1975, Moebius was one of the cofounders of "Metal Hurlant" (Heavy Metal), a spectacular blend of visually arresting comic-book art that was heavily inspired by the counter-culture vibe from across the Atlantic.
The magazine's blend of science fiction, epic fantasy and politically incorrect humour -- which featured in a 1981 animated film of the same name -- provided the perfect platform for Moebius' far-out creations.
As his reputation grew, he collaborated with US comic-books legend Stan Lee on an adventure featuring the enigmatic The Silver Surfer character.
And in another style entirely, he tackled the story of Icarus with Jiro Taniguchi, a master in the Japanese manga tradition.
His influence also spread into cinema, as he put his visual stamp on the first "Alien" film and the science fiction adventure "Tron".
In 2010-11 France's Cartier Foundation for Contemporary Art acknowledged his stature, staging a major retrospective of his work.
Giraud was born in Nogent-sur-Marne east of Paris on May 8, 1938.
After art school he began training as an illustrator for advertisers and the fashion industry before turning to comic strips.
"My ambition was tremendous," he once told AFP. "I wanted to rock, so everybody in the comic industry would be stunned."
Tributes were quick to come in as news of his death spread.
Fellow artist Boucq told AFP his friend Moebius had been a "master of realist drawing" with "a real talent for humour, which he was still demonstrating with the nurses when I saw him in his hospital bed a fortnight ago".
Brazilian author Paulo Coelho, whose bestselling 1995 novel "The Alchemist" was illustrated by Moebius, paid tribute to his collaborator on Twitter.
"The great Moebius died today, but the great Moebius is still alive," he tweeted.
"Your body died today, your work is more alive than ever."
Benoit Mouchart, artistic director at France's Angouleme International Comics Festival, compared him to artistic giants such as Germany's Albrecht Durer and France's Jean-Auguste-Dominique Ingres.
"France has lost one of its best known artists in the world," Mouchart told AFP. "In Japan, Italy, in the United States he is an incredible star who influenced world comics.
"Moebius will remain part of the history of drawing, in the same right as Durer or Ingres," he added.
"He was an incredible producer, he said he wanted to show what eyes do not always see."
French Culture Minister Frederic Mitterrand said France had lost "two great artists", referring to Giraud and his alias.
In 2007 one of his drawings sold for 58,242 euros ($76,433) at an auction.
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