Donald Arthur Berry (born May 26, 1940) is an American statistician and a practitioner and proponent of Bayesian statistics in medical science. He was the chairman of the Department of Biostatistics and Applied Mathematics at the University of Texas M. D. Anderson Cancer Center from 1999-2010, where he played a role in the use of Bayesian methods to develop innovative, adaptive clinical trials. He is best known for the development of statistical theory relating to the design of clinical trials. He is a fellow of the American Statistical Association and the Institute of Mathematical Sciences. He founded Berry Consultants, a statistical consulting group, with Scott Berry in 2000.