George Klein was a Hungarian–Swedish microbiologist and public intellectual. Specializing in cancer research, he was professor of tumour biology at the Karolinska Institute in Stockholm from 1957 to 1992, a chair created for him, and as professor emeritus continued to work as research group leader in the microbiology and tumor biology center. According to Nature, the department Klein founded was "international and influential". In the 1960s he and his wife, Eva Klein, "laid the foundation for modern tumour immunology".

The Alfred P. Sloan Jr. Prize was a $250,000 award given by the General Motors Cancer Research Foundation for outstanding oncological research.