Joseph Schlessinger (born 26 March 1945) is a Croatia-born Israeli biochemist and biophysician. He is chair of the Pharmacology Department at Yale University School of Medicine in New Haven, Connecticut, as well as the founding director of the school's new Cancer Biology Institute.His area of research is signaling through tyrosine phosphorylation, which is important in many areas of cellular regulation, especially growth control and cancer.

 Schlessinger's work has led to an understanding of the mechanism of transmembrane signaling by receptor tyrosine kinases and how the resulting signals control cell growth and differentiation.He received 2014 BBVA Foundation Frontiers of Knowledge Award in the Biomedicine category for “carving out the path that led to the development of a new class of successful cancer drugs.”