David J. DeWitt (July 20, 1948) is a computer scientist specializing in database management system research at the Massachusetts Institute of Technology. Prior to moving to MIT, DeWitt was the John P. Morgridge Professor (Emeritus) of Computer Sciences at the University of Wisconsin–Madison. He was also a Technical Fellow at Microsoft, leading the Microsoft Jim Gray Systems Lab at Madison, Wisconsin. Professor DeWitt received a B.A. degree from Colgate University in 1970, and a Ph.D. from the University of Michigan in 1976. He then joined the University of Wisconsin-Madison and started the Wisconsin Database Group, which he led for more than 30 years.

Professor DeWitt is known for his research in the areas of parallel databases, benchmarking, object-oriented databases, and XML databases.

He was elected a member of the National Academy of Engineering (1998) for the theory and construction of database systems. He is also a Fellow of the Association for Computing Machinery.

He received the ACM SIGMOD Innovations Award (now renamed SIGMOD Edgar F. Codd Innovations Award) in 1995 for his contributions to the database systems field. In 2009, ACM recognized the seminal contributions of his Gamma parallel database system project with the ACM Software System Award. Also in 2009, he received the IEEE Emanuel R. Piore Award for his contributions to the database systems field.