Dr. Jay M. Gregg (b. 1951, Pittsburgh, PA) is Professor Emeritus of Geology at Oklahoma State University in Stillwater, Oklahoma where he was Professor of Geology and held the V. Brown Monnett Chair of Petroleum Geology (2005-2021). He was Head of the Boone Pickens School of Geology at Oklahoma State University from 2005 to 2013. Gregg completed his B.S. degree in 1974 from Bowling Green State University with a double major in Geology and Biology. He received an M.S. in Geology from Oklahoma State University (1976) and a Ph.D. in Geology from Michigan State University (1982). Prior to joining the faculty at Oklahoma State, Gregg worked in the petroleum industry for Sun Production Company (Sunoco) in Midland, TX (1976 to 1978), the minerals industry for St. Joe Minerals Corporation in Viburnum, MO and Tucson, AZ (1982 to 1987), on the nuclear waste repository project in Richland, WA (1987 to 1988), and as a faculty member and later Chair of the Department of Geological Sciences and Engineering at the University of Missouri–Rolla (1988-2005).

Gregg's professional expertise are in the fields of sedimentology, stratigraphy, and geochemistry. He applies this to research toward understanding the origin and diagenesis of dolomite, the diagenetic history of sedimentary basins, and the origin and distribution of sediment hosted base metals and hydrocarbons. He has authored or co-authored more than 100 professional technical papers on these subjects. Gregg's Ph.D. dissertation at Michigan State University involved the description and origin of dolomite crystal textures. This work was supervised by Dr. Duncan F. Sibley and resulted in the publication of the dolomite textural classification system that is in general use in sedimentary petrology textbooks.

Since 1982 much of Gregg's research has been on the flow of mineralizing and hydrocarbon bearing fluids through Paleozoic carbonates of the Mid-Continent of North America and the British Isles. He has also continued his work on dolomite textures in these rocks and in Holocene carbonates in the Caribbean region. In 1995 and 1996 Gregg was the recipient of a Fulbright Scholarship for lecturing and research at University College Dublin, Ireland. At this time he began work on the Lower Carboniferous carbonate hosted base metal deposits of the Irish Midlands. In 1997 Gregg was a Visiting Professor of Geology at the University of the Western Cape in Cape Town, South Africa. This trip resulted in a research project on the Archean age sedimentary dolomites of the Bushy Park area, Northern Cape Province. In April and May, 2005 Gregg took part in the Integrated Ocean Drilling Program (IODP) Expedition 307 to the Porcupine Seabight area of the North Atlantic Ocean. The object of this expedition was to core the Neogene, deep, cold water coral/mud mounds that have been discovered in this area. Gregg spent a sabbatical year (2012-13) working with the Royal Dutch Shell Carbonate Research team in Rijswijk, Netherlands. During his industry and academic career, Gregg has worked on carbonate rocks spanning from Archean to Holocene age on every continent except Antarctica and has mentored numerous undergraduate and graduate students and postdoctoral researchers. As an emeritus professor, Gregg continues working on the diagenesis of carbonate rocks and the origin of dolomite.

Gregg is a Fellow of the Geological Society of America and a member of the American Association of Petroleum Geologists, Society for Sedimentary Geology, International Association of Sedimentologists, Sigma Xi, and the American Association for the Advancement of Science.

Jay M. Gregg has been married to Elizabeth M. Prudot since 1977 and they have three children: Patricia, who is a geophysics at University of Illinois, Nicholas, who is a geophysicist, and Jay W., who works in the IT industry.

Gregg has a semi-professional interest in the history of science, particularly of the history of geology. His hobbies include philately and photography.