The 2015 Labour Party leadership election was triggered by the resignation of Ed Miliband as Leader of the Labour Party on 8 May 2015, following the party's defeat at the 2015 general election. Harriet Harman, the Deputy Leader, became Acting Leader but announced that she would stand down following the leadership election. It was won by Jeremy Corbyn in the first round. Coterminous with the leadership election, in the 2015 Labour Party deputy leadership election, Tom Watson was elected to succeed Harman as deputy leader.

Edward Samuel Miliband is a British politician serving as Shadow Secretary of State for Energy Security and Net Zero since 2021. He has been the Member of Parliament (MP) for Doncaster North since 2005. Miliband was Leader of the Labour Party and Leader of the Opposition between 2010 and 2015. Alongside his brother, Foreign Secretary David Miliband, he served in the Cabinet from 2007 to 2010 under Prime Minister Gordon Brown.