George Alan Kaysen, MD, PhD (1943–2026), was an internationally recognized physician-scientist whose work helped define our modern understanding of protein metabolism, inflammation, and nutritional disorders in kidney disease. Over a distinguished academic career that included leadership positions at the University of California, San Francisco, the Veterans Administration Medical Center in Martinez, and the University of California, Davis, he made foundational contributions to the study of albumin kinetics, lipoprotein metabolism, nephrotic-range proteinuria, dialysis-associated metabolic derangements, protein-energy wasting, sarcopenia, and frailty.