Christopher Earls Brennen was born in Belfast, Northern Ireland, and educated at Oxford University. He joined the faculty of the California Institute of Technology in 1969 and retired in 2010 as the Richard L. and Dorothy M. Hayman Professor of Mechanical Engineering, Emeritus. During his Caltech career, he also served as Vice-President for Student Affairs, Executive Officer for Mechanical Engineering, Dean of Students and Master of Student Houses. He is the author of over 250 technical papers in cavitation, turbomachinery, multiphase and granular flows. He is also the sole author of four popular technical books, "Cavitation and Bubble Dynamics", "Hydrodynamics of Pumps", "Fundamentals of Multiphase Flow" and "Thermo-hydraulics of Nuclear Reactors" (with many foreign language translations). His professional accolades include the Fluids Engineering Awards from both ASME and JSME, NASA's New Technology Award, and the Feynman Prize, Caltech's highest teaching honor. An avid outdoorsman, he received the American Canyoneering Society's John Wesley Powell Award for his contributions to the sport of canyoneering, including widely-used internet guide books.