Dame Trelise Pamela Cooper DNZM (née Neill) is a fashion designer from New Zealand.Her designs have featured in magazines such as Vogue, Marie Claire, Women's Wear Daily, InStyle and the television series Sex and the City.

Cooper was born to Joe and Pam Neill, and grew up in Henderson, West Auckland.She attended Henderson High School, and volunteered at Lifeline crisis support service as a teenager.She left school at the age of 15 and married two years later. She and her husband ran a building business together, but the marriage ended in divorce when Cooper was 21.

Cooper's design business began in the early 1980s, with her first boutique opening in 1985. She then took a break from business to have a baby, and returned in late 1996.

Cooper creates five clothing ranges - Trelise Cooper, Cooper by Trelise, COOP, Board Room and Trelise Cooper Kids, all of which she shows at New Zealand Fashion Week. Customers include Liv Tyler, Miley Cyrus, Lindsay Lohan, Stevie Nicks, Suri Cruise,Julia Roberts, and The Pussycat Dolls. She also produces Trelise Cooper Interiors, a fabric range made in association with textiles house Charles Parsons.

Cooper's signature fragrance 'Trelise' was launched in late 2009. It was designed by perfumer Yves Dombrowsky and has been described as an uplifting, positive scent.

In March 2009, she became the first New Zealand designer to stage a fashion show on board the Queen Mary 2 cruise ship.

Cooper is a patron of the Breast Cancer Research Trust, an advocate for domestic violence awareness and supports Habitat for Humanity. At 2009's New Zealand Fashion Week Cooper initiated an onsite house build to promote this charity.

She is also an environmental supporter, producing eco bags for supermarket chain Progressive Enterprises.She is involved with the UN-sponsored organisation MARITAGE International, which connects young women in developed and developing countries, and also mentors young people in New Zealand.

In December 2005, Cooper was involved in an intellectual property dispute with fellow New Zealand fashion designer Tamsin Cooper, objecting to Tamsin registering her name as a trademark. In July 2007, Cooper agreed to drop the suit and let Tamsin Cooper operate under her own name.

As of 2016, Cooper has 10 boutiques around the world, and her ranges are stocked in more than 200 stores in Australasia, Asia, Europe, America and the Middle East.

The Trelise Cooper Kids Auckland flagship store won the supreme award at the 2007 New Zealand Retail Interior Design Awards.

In 2004, Cooper was named a Member of the New Zealand Order of Merit. In the 2014 New Year Honours, she was elevated to Dame Companion in the same Order.

In 2015, Cooper announced that it will be her final year as a manager.