Siobhán Emma Donaghy (born 14 June 1984) is an English singer-songwriter. She was a founding member of girl group the Sugababes and Mutya Keisha Siobhan. Donaghy left the Sugababes in 2001 following arguments and accusations in the trio with Keisha Buchanan. Donaghy 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 will not be able to release music under the name "Sugababes" as it is still owned by the management company. They will instead release music under the new name, Mutya Keisha Siobhan.