Barry Innis Posner, OC CQ FRSC (born November 7, 1937) is a Canadian physician, research scientist and Professor Emeritus in the Departments of Medicine and Anatomy & Cell Biology at McGill University, where he also managed the Polypeptide and Protein Hormone Laboratory.
He has served as Director of the McGill Endocrine training program and physician-in-chief at the Sir Mortimer B. Davis Jewish General Hospital from 1996 to 2002.
In the late 1980s, he discovered the peroxovanadium compounds as potent insulin mimetics; and in elucidating their mechanism of action, he defined the key role of phosphotyrosine phosphatases in regulating receptor tyrosine kinases.
His group went on to define the role of lipid rafts as sites of intense signaling at both the cell surface and within endosomes.
In 2014, he was made a Knight of the National Order of Quebec; and in 2015 received the Lifetime Achievement Award of the Canadian Diabetes Association.