Prof. Viktor Ambartsumian (1908-1996) is one of the greatest scientists of the XX century, the greatest Soviet astrophysicist and the founder of the theoretical astrophysics school in the USSR that has fundamentally contributed to various fields of astronomy and astrophysics, cosmogony, theoretical physics, mathematics, and philosophy. His revolutionary works on stellar evolution and activity of galactic nuclei turned over the development of astrophysics and gave life to our before unchanged Universe. Ambartsumian was also a great organizer of science, important political and public figure. He was the founder of the astrophysics departments at the Leningrad (St. Petersburg) and Yerevan State Universities, the Byurakan Astrophysical Observatory (BAO), journal Astrofizika (Astrophysics), one of the founders of the Armenian Academy of Sciences. Ambartsumian was the Director of BAO in 1946-1988, the President of the Armenian Academy of Sciences in 1947-1993, the President of the International Astronomical Union in 1961-1964 and the President of the International Council of Scientific Unions (ICSU) in 1968-1972.