Siobhán Emma Donaghy (born 14 June 1984) is an Irish-English singer-songwriter. She is a founding member of the girl group Sugababes. Donaghy left the Sugababes in 2001 and released her debut solo album, Revolution in Me, on 23 September 2003, which contained three single releases. Her second studio album, Ghosts, was released on 25 June 2007. Donaghy appeared in a remixed version of the hit stage show Rent (titled Rent Remixed) for its 2007–2008 run, playing the role of Mimi alongside Denise van Outen.
On 20 July 2012, Donaghy and her former Sugababes colleagues, Buena and 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.