Alexander McQueen, the British fashion designer known for some of the most controversial collections of the last two decades, was found dead Thursday morning at his apartment in London, said Ed Filipowski, a partner in the public relations firm KCD.

The cause was apparently suicide, though Mr. Filipowski said Mr. McQueen’s family had not yet made a statement.

For five years, until 2001, he also was the designer of the couture label Givenchy, where he turned the classic French house on its head, often drawing the ire of longtime fans of the label known for its elegant black dresses. He offended several French journalists for calling Hubert de Givenchy’s past work as “irrelevant.” That year, he sold his own label to the Gucci Group, a rival of the parent company of Givenchy, LVMH, following several conflicts with its management.

During his early days in London, Mr. McQueen’s collections often made audiences uncomfortable, as when he referenced the ravaging of Scotland by England by showing brutalized women in a collection called “Highland Rape.” But since he began showing his collections in Paris in 2001, he became more widely respected for designs that were seen as commentary on the often surreal, and self-referential, world of fashion.