Sarah Nicole Harding (born 17 November 1981, in Ascot) is an English singer in the girl group Girls Aloud, and model. Harding grew up as a Catholic in Poynton, Stockport, Greater Manchester, England, and is the oldest member of Girls Aloud. Harding attended Hazel Grove High School and Stockport College, she worked as part of the promotions team for 2 nightclubs in The Grand Central Leisure Park in Stockport.

Harding was also a regular singer at Karaoke nights in the Whistling Jig, Puss and Boots pub as well as many others and did some vocals for Project G on some unreleased tracks. Project G was a band for which Harding provided backing vocals, long before Girls Aloud came along. She did some photoshoots for promotion but no album, nor known singles exist. Some tracks that have leaked onto the internet include "Searching" and "Don't Wanna Be Alone". Whilst working as a waitress and barmaid in Manchester, she entered the UK talent-search show Popstars: The Rivals.

Harding also entered FHM's High Street Honeys, the magazine's national beauty contest, and her pictures appeared in the first Top 100, but she later withdrew, upon achieving success on Popstars. A year later, she was voted one of the Top 30 sexiest women in the world, by readers of the same magazine. In 2005, she entered the same Top 10 at Number 8, slipping to Number 15 in 2006, and to Number 17 in 2007. In the finale of the "Popstars" show, she was picked as the final member of the five-piece group, Girls Aloud, that formed the female half of the eponymous 'rivals'. She defeated Javine Hylton for the final place, in a result that provoked a measure of surprise and controvers

As a member of Girls Aloud, Harding has taken part in many events and TV shows, such as the August 25, 2006 episode of The Friday Night Project. Sarah co-hosted the show with Cheryl Cole and Kimberley Walsh. During her time with the group she has co-written numerous songs, including "Hear Me Out", which appeared on the group's second album What Will The Neighbours Say?. She's also credited as one of the writers of "Why Do It?", the b-side for "I Think We're Alone Now" single. Outside of Girls Aloud, Harding signed a £100,000 deal to model Ultimo lingerie, following the likes of Penny Lancaster, Rachel Hunter and Helena Christensen. Reports claim that Sarah was chosen to model the underwear range after she was seen wearing a bikini on holiday in the paper

Harding has filmed a cameo appearance in a British independent film called Bad Day, due for release in 2007. She plays a brunette girl called Jade Jennings who sits in the back of a cab and swears down the phone. The film also stars Donna Air and Claire Goose. Harding has recently been seen as the face of Coke Zero, upon its launch in Ireland. She will also advertise and promote Sunsilk with the rest of Girls Aloud.