Chaudhary Aitzaz Ahsan (born 27 September 1945) is a Pakistani politician and lawyer. He served as the Leader of the House in the Senate of Pakistan from 1994 to 1996, and as the Leader of the Opposition from 1996 till 2000 and again from 2012 to 2018. He was elected a member of the Senate of Pakistan from Punjab in 1994. His tenure ended in March 2018.

Born in Murree, Ahsan studied law at the Government College, Lahore and received a LLM from the Downing College, Cambridge. Ahsan became the Planning and Development Minister for Punjab in 1975. After the Operation Fair Play coup, Ahsan became a prominent figure of the Movement for the Restoration of Democracy. Ahsan was elected to the National Assembly from Lahore in 1988 and served as the interior minister of Pakistan under Benazir Bhutto’s first government and served until 1990.

Ahsan was elected as a member of the Senate in 1994. He re-joined the cabinet after Benazir’s re-election, and went on to serve as the Minister for Law, Justice and Human Rights until 1997. He served as the minority leader in the Senate between 1996 and 1999. Ahsan was elected to the National Assembly again in 2002, and went on to serve as the president of the Supreme Court Bar Association between 2007 and 2008. Ahsan was elected to the Senate in 2012 and in 2015 became the minority leader.

Professionally, Ahsan is a barrister by law and a senior advocate of the Supreme Court of Pakistan. He is a senior partner of Aitzaz Ahsan & Associates. Ahsan has represented several high-profile Pakistani personalities including three Prime ministers of Pakistan in various cases such as Nawaz Sharif, Benazir Bhutto and Yousaf Raza Gillani and former President of Pakistan Asif Ali Zardari. He had served as President of Supreme Court Bar Association of Pakistan.

He is known for representing and leading the lawyers campaign to reinstate former Chief Justice of Pakistan Iftikhar Muhammad Chaudhry. In 2008, Ahsan was awarded the Asian Human Rights Defender Award by the Hong Kong-based Asian Human Rights Commission in recognition. Ahsan was arrested following Pakistani state of emergency, 2007. He was house arrest in his house in Lahore for four months. He was released in March 2008. Ahsan is also a noted human rights activist in Pakistan.

Ahsan is the author of the book The Indus Saga and the Making of Pakistan and its Urdu translation, Sindh Sagar Aur Qyam-e-Pakistan which presents the cultural history of Pakistan and argues that the Indus region is a distinct entity from the rest of India and constitutes a nation.

He has also co-authored the book Divided by Democracy with Lord Meghnad Desai of the London School of Economics.