Baitullah Mehsud (Pashto: بیت اللہ محسود; Urdu: بیت اللہ محسود; c. 1974 – August 2009) was a leading militant in Waziristan, Pakistan, and the leader of the Taliban umbrella group, Tehrik-i-Taliban Pakistan, which he formed from an alliance of about five pro-Taliban groups in December 2007. He is thought by U.S. military analysts to have commanded up to 5,000 fighters and to have been behind numerous attacks in Pakistan including the assassination of Benazir Bhutto.

Disagreement exists over the exact date of the militant's death. Pakistani security officials initially announced that Baitullah Mehsud, his wife and bodyguards were killed on 5 August 2009 in a CIA drone attack in the Zangar area of South Waziristan. Interior Minister Rehman Malik delayed giving official confirmation and asked for patience and an announcement by ISPR or other agencies. Kafayat Ullah, a Taliban source, also announced the death of the militant in the strike, as did his deputy Faqir Mohammed. Later Taliban commander Hakimullah Mehsud denied previous TTP announcements and said Mehsud was in good health. Major General Athar Abbas, ISPR spokesman, and Robert Gibbs of the White House said his death could not be confirmed, U.S. National Security Adviser James L. Jones also claimed that there was "pretty conclusive" evidence that proved Baitullah Mehsud had been killed and that he was 90% sure of it. On August 25, 2009, Hakimullah Mehsud and Wali-ur-Rehman telephoned the BBC to say that the militant had died on August 23, 2009, due to injuries sustained during the August 5 attack. The BBC received a video that shows the body of Mehsud on September 30.

Syed Saleem Shahzad, writing in the Asia Times, described Baitullah Mehsud as a physically small man, with diabetes.