Peter Agre (/ˈɑːɡriː/; born January 30, 1949) is a Nobel Laureate American physician, molecular biologist, Bloomberg Distinguished Professor at the Johns Hopkins Bloomberg School of Public Health and Johns Hopkins School of Medicine, and director of the Johns Hopkins Malaria Research Institute. In 2003, Agre and Roderick MacKinnon shared the 2003 Nobel Prize in Chemistry for "discoveries concerning channels in cell membranes." Agre was recognized for his discovery of aquaporin water channels. Aquaporins are water-channel proteins that move water molecules through the cell membrane. In 2009, Agre was elected president of the American Association for the Advancement of Science (AAAS) and became active in science diplomacy.

Agre was born in Northfield, Minnesota and is the second of six children to parents of Norwegian and Swedish descent. Agre is a Lutheran. Fascinated by international travel after a high school camping trip through the Soviet Union, Agre was an inconsistent student until he developed an interest in science from his father who was a college chemistry professor.

Agre graduated from Roosevelt High School (Minnesota) before he received his B.A. in Chemistry from Augsburg University in Minneapolis and his M.D. in 1974 from the Johns Hopkins School of Medicine in Baltimore, Maryland. From 1975 to 1978, he completed his clinical training in Internal Medicine at Case Western Reserve University's Case Medical Center under Charles C.J. Carpenter. He subsequently did a Hematology-Oncology fellowship at North Carolina Memorial Hospital of UNC Chapel Hill. In 1981, Agre returned to the Johns Hopkins School of Medicine to join the lab of Vann Bennett in the Department of Cell Biology.

In 1984, Agre was recruited to the faculty of the Department of Medicine led by Victor A. McKusick. He subsequently joined the Department of Biological Chemistry led by Dan Lane. Agre rose to full professor in 1992 and remained at Johns Hopkins until 2005. Agre then served as the Vice Chancellor for Science and Technology at Duke University Medical Center in Durham, North Carolina, where he guided the development of Duke's biomedical research. In 2008, he returned to Johns Hopkins, where he directs the Johns Hopkins Malaria Research Institute (JHMRI) in the Johns Hopkins Bloomberg School of Public Health and holds a joint appointment in the Johns Hopkins School of Medicine.

In 2004, Agre received the Golden Plate Award of the American Academy of Achievement. In February 2014, he was named a Bloomberg Distinguished Professor at Johns Hopkins University for his accomplishments as an interdisciplinary researcher and excellence in teaching the next generation of scholars. The Bloomberg Distinguished Professorships were established in 2013 by a gift from Michael Bloomberg.

Agre and his wife, Mary, have been married since 1975. They have three daughters, one son, and two young granddaughters. Agre is an Eagle Scout and recipient of the Distinguished Eagle Scout Award (DESA). Two of his brothers, also physicians, and his son Clarke, a public defender, are also Eagle Scouts. Agre enjoys wilderness canoeing in the arctic and cross-country skiing, having completed the 60 mile Vasaloppet ski race in Sweden five times. Diagnosed with Parkinson's disease in 2012, Agre has had to reduce his activities.

"I identify more with Huckleberry Finn than with Albert Einstein," he told Scouting magazine.

Agre is known among science students for his humanity and humility. He appeared on The Colbert Report, discussing his role as a founding member of Scientists and Engineers for America (SEA), sound science in politics, and the decline of American knowledge of science, among other topics.