Mohammad Qasim Fahim (محمد قسيم فهيم) was the defense minister of the Afghan Transitional Administration, beginning in 2002. He also served as deputy prime minister. He was removed as defense minister by President Hamid Karzai on December 23, 2004, as the transitional administration gave way to a popularly-elected administration.

While holding the position, he continued to command his own militia. However, on December 10, 2003, he ordered part of his militia to transport their weapons (including 11 tanks, 10 rocket-launchers and two scud missiles) to an Afghan National Army installation near Kabul.

Prior to the fall of the Taliban, Fahim was a factional leader of the Northern Alliance. On September 13, 2001, Fahim was confirmed as the senior military commander of the Northern Alliance, succeeding Ahmad Shah Masood. Masood had been assassinated four days earlier. By September 22, Fahim was in Tajikistan holding talks with Russian army chief Anatoly Kvashnin.

As defense minister he toured army bases in the United Kingdom, negotiated security issues with U.S. General Tommy Franks and Canadian Defense Minister John McCallum, NATO Secretary General George Robertson, visited Moscow and Washington, DC. He also replaced 15 ethnic Tajik generals with officers from the Pashtun, Uzbek and Hazara ethnic groups.

In June of 2003, a bomb was found in front of his home. Later in the year, the head of his personal security died at the hands of a suicide bomber.

On September 12, 2003, Miloon Kothari, appointed by the United Nations Commission on Human Rights to investigate housing rights in Afghanistan, announced that Fahim and Education Minister Yunus Qanuni were illegally occupying land and should be removed from their posts. However, three days later, Kothari sent a letter to Lakhdar Brahimi, the head of the U.N. in Afghanistan, saying he had gone too far in naming the ministers.