Seumas Patrick Charles Milne is an English journalist and political aide. He was appointed as the Labour Party's Executive Director of Strategy and Communications in October 2015 under Labour Party Leader Jeremy Corbyn, initially on leave from The Guardian. In January 2017, he left The Guardian in order to work for the party full-time. He left the role upon Corbyn's departure as leader in April 2020.

Milne joined The Guardian in 1984. He was a columnist and associate editor there at the time of his Labour Party appointment, and according to Peter Popham writing for The Independent in 1997, was "on the far left of the Labour Party." Milne is the author of The Enemy Within: The Secret War Against the Miners, a book about the 1984–1985 UK miners' strike which focuses on the role of MI5 and Special Branch in the dispute.