Karl Ziegler Morgan (September 27, 1907 – June 8, 1999), was an American physicist who was one of the founders of the field of radiation health physics.

He was director of health physics at Oak Ridge National Laboratory from the time in the Manhattan Project late 1940s until his retirement in 1972.

He began an academic career as a faculty member at Lenoir Rhyne College, but in 1943 was recruited to work in the secret project to develop an atomic bomb.

[1][2][3] Initially at the University of Chicago Metallurgical Laboratory and later in Oak Ridge, Morgan joined a small group of physicists who were interested in the health effects of radiation.

[4] Morgan became director of health physics at Oak Ridge National Laboratory (ORNL), serving from the late 1940s until his retirement in 1972.