Alastair John Campbell is a British journalist, author, strategist, broadcaster, and activist, who is known for his political roles during Tony Blair's leadership of the Labour Party. Campbell worked as Blair's spokesman and campaign director in opposition (1994–1997), then as Downing Street Press Secretary, and as the Prime Minister's Official Spokesperson (1997–2000). He then became Downing Street's director of communications and spokesman for the Labour Party (2000–2003).

Since his work for Blair, Campbell has continued to act as a freelance advisor to a number of governments and political parties, including Edi Rama, the Prime Minister of Albania. He was an adviser to the People's Vote campaign, campaigning for a public vote on the final Brexit deal. He is the editor-at-large of The New European and chief interviewer for GQ. He acts as a consultant strategist and as an ambassador for Time to Change and other mental health charities. Throughout his time in Downing Street, Campbell kept a diary which reportedly totalled some two million words. Selected extracts, titled The Blair Years, were published in 2007. He expressed an intention to publish the diaries in fuller form, which he did from 2010 to 2018. In 2019, Campbell was expelled from the Labour Party after voting for the Liberal Democrats in that month's European elections. In 2022, Campbell launched the podcast The Rest Is Politics with Rory Stewart, which has been the top politics podcast in the UK in the Apple rankings since its launch.