Dr. prof. Abdul Qadeer Khan or A. Q. Khan- Hilal-i-Imtiaz (HI), Nishan-i-Imtiaz (NI) (twice), (Urdu: عبدالقدیر خان; born April 27, 1936 in Bhopal, British India) is a Pakistani nuclear scientist and metallurgical engineer, widely regarded as the founder of Pakistan's nuclear program. His middle name is occasionally rendered as Quadeer, Qadir or Qadeer, and his given names are usually abbreviated to A.Q. Some people refer to him as Mohsin-e-Pakistan (saviour/benefactor of Pakistan) (Urdu: محسنِ پاکستان) in his country. However, Khan is perhaps better known in much of the world for his involvement in nuclear proliferation - involvement in acquiring critical nuclear technology designs and using them to build Pakistan's nuclear arsenal, as well as selling this technology to Libya, Iran and North Korea. Some of his critics have described him as the "Terror Trader" and the "Klaus Fuchs of Pakistan".

In January 2004, Khan confessed to having been involved in a clandestine international network of nuclear weapons technology proliferation from Pakistan to Libya, Iran and North Korea. There is evidence to believe that Khan and his network are one of the worst proliferators of nuclear technology that can be used to develop nuclear weapons. However, owing to domestic pressure from radical groups, on February 5, 2004, the President of Pakistan, General Pervez Musharraf, announced that he had pardoned Khan. Khan is widely seen as a national hero in Pakistan for helping Muslim countries develop nuclear weapons.

In an August 23, 2005 interview with Kyodo News General Pervez Musharraf confirmed that Khan had supplied gas centrifuges and gas centrifuge parts to North Korea and, possibly, an amount of uranium hexafluoride.