Peter Gary Tatchell (born 25 January 1952) is an Australian-born British human rights campaigner who has devoted his career to advancing LGBTQ rights and social justice causes. He first entered the political arena as Labour's parliamentary candidate for Bermondsey in 1981, though he was publicly denounced by party leader Michael Foot for reportedly supporting extra-Parliamentary action against the Thatcher government. Despite being allowed to contest the February 1983 Bermondsey by-election, Labour lost the seat to the Liberals. In the 1990s, Tatchell co-founded the direct action group OutRage!, through which he campaigned vigorously for LGBTQ rights, and later led the Stop Murder Music campaign against lyrics inciting violence against LGBT people. His activism has included bold attempts to arrest Zimbabwean President Robert Mugabe in 1999 and 2001.

Tatchell joined the Green Party of England and Wales in April 2004 and was selected as prospective Parliamentary candidate for Oxford East in 2007, though he stood down in December 2009 due to brain damage sustained largely during protests and from a bus accident. Since 2011, he has served as Director of the Peter Tatchell Foundation and has participated in over thirty debates at the Oxford Union on subjects ranging from patriotism to university safe spaces. He writes commentary for Comment Central.