Oswald Theodore Avery was a Canadian-born American physician and medical researcher. The major part of his career was spent at the Rockefeller University Hospital in New York City. Avery was one of the first molecular biologists and was a pioneer in immunochemistry, but he is best known for his discovery in 1944 with his co-workers Colin MacLeod and Maclyn McCarty that DNA is the material of which genes and chromosomes are made.

The Nobel laureate Arne Tiselius said that Avery was the most deserving scientist not to receive the Nobel Prize for his work.