Diane Monique Lhuillier (born 1971 in Cebu City, Cebu, Philippines) is a Filipino fashion designer based in the United States. She was born and raised in the Philippine province of Cebu and is of French and Cebuano descent, hence her typical French last name meaning "the oilmaker".
Lhuillier's family is one of the more prominent names in Philippine high society. The family owns a chain of pawnshops currently operating in more than a hundred cities in the nation.
Having had a difficult time finding her own gown, Lhuillier, a 23-year-old newlywed at the time, decided to begin sketching her own line of dresses. Her husband figured it was little more than a hobby, one that she would tire of soon enough. "He thought I had the wedding blues and eventually I'd get over it," she told USA WEEKEND Magazine. 
She made the news with two high-profile celebrity weddings in a row. She designed Christine Baumgartner's wedding dress for the fall 2004 wedding to Kevin Costner shortly after designing both of Britney Spears's wedding dresses in her wedding to Kevin Federline. She's also designed the wedding gown of US former Vice President and former Second Lady Al and Tipper Gore's youngest daughter, Sarah G. Lee, during her marriage to Bill Lee, Giuliana DePandi's wedding gown to The Apprentice winner Bill Rancic, and Allison Munn's wedding gown to actor Scott Holroyd.
Subsequently Lhuillier added evening wear to her line, and several of her efforts showed up on red carpets before awards shows. For the Fall 2007 season she branched off into more typical oddball runway collections.