Siobhán Emma Donaghy (born 14 June 1984) is an English singer and songwriter, best known as a founding member of the girl group Sugababes. Donaghy left Sugababes in 2001 and released her debut solo album, Revolution in Me, in 2003. Her second studio album, Ghosts, was released in 2007 and met critical acclaim.

In 2012, Donaghy and her former Sugababes bandmates Mutya Buena and Keisha Buchanan confirmed their reunion. The original trio were not able to release music under the name Sugababes as it was still owned by the management company. They instead released music under the new name Mutya Keisha Siobhan, until they secured the legal rights to the Sugababes name again in 2019.