McQueen, 40, was found dead at his home in west London this morning. Scotland Yard is not treating the death as suspicious, but early reports of a suicide have not been confirmed by police.
"We are devastated and in shock," said Samantha Garrett, the communications director for the Alexander McQueen fashion house.
The designer's death comes on the heels of the Feb. 2 passing of his mother, Joyce. McQueen was scheduled to show a new collection in Paris early next month.
McQueen was beloved at the highest levels of fashion as the "enfant terrible" or "anarchist designer" of the industry. He was internationally acclaimed for both his clothes as well as his cutting edge fashion shows, considered by many to be performance art year after year.
His fall 2009 "Witches Collection" was based on the Salem witch trials, and featured models in black wearing smudged lipstick and fantastical headpieces. In 1998, he caused controversy when he sent a double amputee down the catwalk with wooden legs.
"This world I live in, this fashion world, is so unrelated to what's going on around the world," he told the BBC at the time, "So what I try to do is to take parts of the world people in my world don't want to see and bring it to them."
Fashion insiders loved McQueen for his irreverent attitude.
"His brilliant imagination knew no bounds as he conjured up collection after collection of extraordinary designs. At one level he was a master of the fantastic, creating astounding fashions shows that mixed design, technology and performance and on another he was a modern day genius whose gothic aesthetic was adopted by women the world over," said Alexandra Shulman, editor of British VOGUE. "His death is the hugest loss to anyone who knew him and for very many who didn't."
McQueen was favored by some of the most famous names in the fashion world, including Kate Moss, Naomi Campbell and Sarah Jessica Parker. More recently, he dressed Lady Gaga, Rihanna, Bjork and Madonna. McQueen's studded, impossibly high "alien boots" almost steal the show in Lady Gaga's "Bad Romance" video.
He influenced everyday wear as well, introducing low-waisted "bumster" jeans which quickly became a ubiquitous trend.
Alexander McQueen's Celebrity Fans Mourn on Twitter
Many of his famous clients and associates reacted immediately to news of his death via Twitter. Reality TV star Kim Kardashian tweeted, "I just found out Alexander McQueen died!!! I'm in shock! So sad! I'm wearing one of his dresses now! He was such a talented designer."
Celebrity stylist Rachel Zoe echoed, "I can't describe the tragic loss of such a brilliant man and designer Alexander McQueen..R.I.P."
Joe Zee, creative director of Elle magazine, chimed in, ""R.I.P. Alexander McQueen, a kind soul and brilliant creative genius. Sad and shocking. You've touched us all."
Supermodel Tyra Banks added, "RIP Alexander McQueen. so so sad. such a huge loss. He was one of my favorite designers. He will be missed."
McQueen wasn't born as fashion royalty. The son of an East London taxi driver, Lee Alexander McQueen was the youngest of six children in a working class family. He left school at age 16 and went on to train as a tailor on Saville Row for years before entering Central Saint Martins College of Art and Design in 1990. His entire 1992 graduation collection was purchased by the fashion designer Isabella Blow.
In 1996 he became head designer at the fashion label Givenchy. The same year he won the first of four British Designer of the Year awards. In 2000 he partnered with Gucci to open his own stores around the world.
"He was a technical master, he came from a pattern cutting background and his clothes were always extraordinarily crafted," said Prof. Louise Wilson of St. Martins College. "He could push the boundaries because he knew how to do it and he could do it himself. Therefore he took risks with the body and how he dressed it."
McQueen was devastated by the loss of his close friend and early champion Isabella Blow, who committed suicide in 2007. He was not expected to attend events at New York Fashion Week or the upcoming London Fashion Week, though his ready to wear line, McQ, was scheduled to be presented in New York today. That presentation has since been canceled.