Aleksandr Ilyich Akhiezer (Ukrainian: Олекса́ндр Іллі́ч Ахіє́зер, Russian: Алекса́ндр Ильи́ч Ахие́зер; October 18, 1911 – May 4, 2000) was a Soviet and Ukrainian theoretical physicist, known for contributions to numerous branches of theoretical physics, including quantum electrodynamics, nuclear physics, solid state physics, quantum field theory, and the theory of plasma.^[1][2] He was the brother of the mathematician Naum Akhiezer.

Akhiezer was born in Cherykaw, Russian Empire in what is now Mogilev Region, Belarus. He studied radio engineering at Kyiv Polytechnic Institute in 1929–34. From 1934, he worked at the Ukrainian Institute of Physics and Technology in Kharkiv. With Isaak Pomeranchuk and under the supervision of Lev Landau, he studied light-light scattering and was awarded a Ph.D. in 1936.

When Landau left Kharkiv in 1938, Akhiezer became head of the department of Theoretical Physics. A treatise on wave absorption in modulated quasiparticles gave him a habilitation degree in 1941, since when he was full professor at the same place until his death at the age of 89.

With Cyril Sinelnikov and Anton K. Valter he founded the faculty of physics and technology. With Pomeranchuk he studied neutron scattering and plasma physics at the Kurchatov nuclear physics institute in Moscow (1944–52).

• 1949 L. I. Mandelshtam Prize of the Academy of Sciences of the Soviet Union
• 1998 Pomeranchuk Prize

• First Russian book on nuclear reactions (1945)
• Akhiezer, A. I.; Berestetsky, V. B. (1953). Quantum Electrodynamics. U.S. Atomic Energy Commission.
• Landau, L. D; Akhiezer, A. I.; Lifshitz, E.M. (2013) [1965]. General Physics: Mechanics and Molecular Physics. Elsevier Science. ISBN 978-1483285184.
• Akhiezer, A. I.; Peletminskii, S. V.; Baryakhtar, V. G. (1968). Spin waves. North-Holland. ISBN 978-0429971440.
• Evolving physical picture of the world (1973 in Russian; updated version 1996 in English)
• Akhiezer, A. I.; ter Haar, D. (1975). Plasma Electrodynamics. Pergamon Press. ISBN 9780080180168.
• Physics of elementary particles (1979), Elementary Particles (1986) and Biography of elementary particles (1979). With Mikhail P. Rekalo.
• From quanta of light to colour quarks (1993). With Yu. P. Stepanovsky.
• Akhiezer, A. I.; Shulga, N.F. (1996). High Energy Electrodynamics in Matter. Taylor & Francis. ISBN 978-2884490146.
• Akhiezer, A. I.; Akhiezer, I. A.; Polovin, R. V.; Sitenko, A. G.; Stepanov, K.N.; ter Haar, D. (2017) [1975]. Plasma Electrodynamics. Volume 1: Linear Theory. Elsevier Science. ISBN 978-1483152158.
• Akhiezer, A. I.; Akhiezer, I. A.; Polovin, R. V.; Sitenko, A. G.; Stepanov, K.N. (2017) [1975]. Plasma Electrodynamics. Volume 2: Non-Linear Theory and Fluctuations. Elsevier Science. ISBN 978-1483148076.