Joel D. Kopple is an American professor, physician, and clinical investigator in medicine, nephrology, nutrition, and public health. He is professor at David Geffen UCLA School of Medicine and UCLA Fielding School of Public Health. He served from 1982 to 2007 as the chief of the Division of Nephrology and Hypertension at Harbor-UCLA Medical Center. He is also known as the father of the field of Renal Nutrition.