Oswald Theodore Avery Jr. ForMemRS (October 21, 1877 – February 20, 1955) was a Canadian-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 a pioneer in immunochemistry, but he is best known for the experiment (published in 1944 with his co-workers Colin MacLeod and Maclyn McCarty) that isolated DNA as the material of which genes and chromosomes are made.
The Nobel laureate Arne Tiselius said that Avery was the most deserving scientist to not receive the Nobel Prize for his work, though he was nominated for the award throughout the 1930s, 1940s, and 1950s.
The lunar crater Avery was named in his honor.