John William Gregg (January 8, 1880 – April 25, 1969) was an American landscape architect and educator who was instrumental in the establishment and development of landscape architecture as an academic discipline in the United States, particularly in the West.
Gregg was born in Guthrie, Missouri. He received his education at the Massachusetts Agricultural College (now the University of Massachusetts Amherst) and Boston University. Following a period of professional practice and teaching in the Eastern United States and Nebraska, he was recruited by the University of California, Berkeley, in 1913.
At Berkeley, Gregg founded the Division of Landscape Gardening and Floriculture, which later evolved into the Department of Landscape Architecture. He served as the chairman of the department for 33 years until his retirement in 1946. His leadership is credited with professionalizing the study of landscape design in California and aligning it with both horticultural science and environmental planning.
Throughout his career, Gregg was involved in the campus planning of several University of California campuses and provided consultancy for various municipal park systems. He was a prominent member of the American Society of Landscape Architects (ASLA) and was elected a Fellow of the society in 1949 in recognition of his contributions to the field. His legacy is maintained through the John William Gregg Early Career Award and the continued influence of the program he established at Berkeley.