Karen Cook McNally (1940 – December 20, 2014) was an American seismologist. She was born in Clovis, California and received bachelor's (1971) and master's (1973) degrees and a PhD (1976) in geophysics from the University of California, Berkeley. McNally worked at the California Institute of Technology with Charles Francis Richter, creator of the Richter magnitude scale, and became part of the faculty at the University of California, Santa Cruz in 1981. She was director of the Richter Seismological Laboratory there and their instruments were able to capture high-quality recordings of the 1989 Loma Prieta earthquake. She founded the Institute of Tectonics and helped establish a seismology research program at the University.