Charles Herbert Best (February 27, 1899 – March 31, 1978), was an American-Canadian medical scientist and one of the co-discoverers of insulin with Frederick Banting.

[3] His father, Herbert Best, was a doctor in a small Maine town with a limited economy based mostly on sardine-packing.

[3] It was for this reason, and the fact that his father was a physician, that he chose to study at University of Toronto and train to become a doctor.

[5] As a 22-year-old medical student at the University of Toronto he worked as an assistant to the surgeon Dr. Frederick Banting[6] and contributed to the discovery of the pancreatic hormone insulin, which led to an effective treatment for diabetes.

Before leaving for Scotland he supplied Banting with ten dogs for experiment and two medical students, Charles Best and Edward Clark Noble, as lab assistants.

In December 1921, when Banting and Best were having difficulties in refining the pancreatic extract and monitoring glucose levels, MacLeod assigned the biochemist James Collip to the team.

In January 1922, while Collip was working on insulin purification, Best and Banting administered prematurely their pancreatic extracts to 14-year-old Leonard Thompson, who suffered a severe allergic reaction.

After Banting's death, Best "claimed that the crucial innovation of using alcohol to remove toxic impurities had largely been his own", even though this had actually been Collip's key contribution.

[15] During World War II he was influential in establishing a Canadian program for securing and using dried human blood serum.

In his later years, he was an adviser to the Medical Research Committee of the United Nations World Health Organization Best later claimed that the greatest moment of his life occurred when he met his future wife, Margaret Mahon (1900–1988) following his return.

[5] As a recipient of the Order of Canada, he was awarded the Canadian version of the Queen Elizabeth II Silver Jubilee Medal in 1977.