Ronald Melzack OC OQ FRSC (July 19, 1929 – December 22, 2019) was a Canadian psychologist and professor of psychology at McGill University.

In 1968, Melzack published an extension of the gate control theory, in which he asserted that pain is subjective and multidimensional because several parts of the brain contribute to it at the same time.

Donald O. Hebb was Melzack's research advisor at university during the time he worked on his doctoral thesis.

Hebb was doing experiments with dogs who had not been normally socialized and Melzack became interested in their unusual response to pain when they would stick their nose in a flame repeatedly.

While still a postdoctoral student, Melzack began collecting "pain words" and putting them into classes that belonged together, like "hot," "burning," "scalding," and "searing".

Gate control theory led to the valuable discovery of endorphins and enkephalins, the body's natural opiates.

[5] Melzack's recent research at McGill indicates that there are two types of pain, transmitted by two separate sets of pain-signaling pathways in the central nervous system.

Melzack also supervised graduate students at McGill, one of whom —John O'Keefe— would later go on to receive the Nobel Prize in Physiology or Medicine in 2014.

He received the Prix du Québec for research in pure and applied science (1994), recognizing him as a laureate of the highest honor for a scientist in his home province.

On April 29, 2009, he was inducted into the Canadian Medical Hall of Fame, in recognition of his “outstanding contributions to medical science and the improved health and well-being of people everywhere.”[12] Melzack was the recipient of the 2010 University of Louisville Grawemeyer Award in psychology for his studies and explanation of experiencing pain.