Muhammad Raziuddin Siddiqui, FPAS, NI, HI, SI (Urdu: محمد رضی الدین صدیقی, [rəzɪ.ʊd̪ːiːn sɪˈd̪ːiːqi]; 8 January 1908 – 8 January 1998), also known as Dr. Razi, was a Pakistani theoretical physicist and a mathematician who played a role in Pakistan's education system, and Pakistan's indigenous development of nuclear weapons.

After passing the Rashidia Exams in 1918, Siddiqui completed his matriculation from Osmania University in 1921, and earned a Bachelor of Arts (BA) in mathematics, with distinction, in 1925.

[4] Siddiqui was then awarded a scholarship from the Government of the State of Hyderabad to pursue higher studies in United Kingdom where he completed his MA in mathematics, under Paul Dirac from the University of Cambridge in 1928.

[5] He completed his PhD in theoretical physics, writing a brief research thesis on the Theory of relativity and the nuclear binding energy.

[7] During his stay in Great Britain, he studied Quantum mechanics and published scientific papers at the Cavendish Laboratory.

[8] In 1931, Siddiqui then returned to Hyderabad, British Indian Empire, and joined Osmania University there as an associate professor of mathematics.

[8] In 1965, with the establishment of Quaid-e-Azam University (QAU), Siddiqui was appointed as its first vice-chancellor by the then foreign minister Zulfikar Ali Bhutto.

[10] During the 1960s, he helped convince President of Pakistan Ayub Khan to make a proposed university a research institution.

[10] After the Indo-Pakistani War of 1971, Siddiqui joined the Pakistan Atomic Energy Commission (PAEC) at the request of Prime Minister Zulfikar Ali Bhutto.

[12] His Mathematical Physics Group undertook the research and performed calculations on the 'relativity of simultaneity' during the process of weapon detonation, where multiple explosive energy rays are bound to release in the same isolate and close medium at the same time interval.

[8] His eldest daughter, Dr. Shirin Tahir-Kheli, is a former special assistant to the president of the United States of America, and Senior Adviser for women's empowerment.