Hagop Souren Akiskal (Armenian: Հակոբ Սուրեն Ակիսկալ, born 1944) is an Armenian-American psychiatrist best known for his research on temperament and bipolar disorder (manic depression). Born in Lebanon to Armenian parents, he received his M.D. from the American University of Beirut in 1969. He completed his residency training in psychiatry at University of Wisconsin–Madison, and then worked for several years as a clinician and mood disorders researcher at the University of Tennessee, Memphis. He was senior science advisor at NIMH from 1990–1994, before moving to the University of California, San Diego, where he is currently professor of psychiatry. Today's leading conceptual thinker in the area of bipolar subtyping, Akiskal is a fastidious researcher and an astute clinical observer. He is a devotee of Emil Kraepelin; he believes that the nosologic (classification) pendulum is gradually swinging back towards Kraepelin's original unitary concept of the bipolar spectrum of mood disorders (Lieber, Arnold).