Jonas Salk made the discovery of the Polio Vaccine. His discovery helped people from dying and or crippling.
Ben Carson was the first man and African American to preform brian surgery to stop seizures. He was also the first to seperate siamese twins, and do hemispherectomies.
Karl Landsteiner was the discoverer of blood types A, AB, and o. Without this discovery of the various blood types people would die because without the right blood type blood will clot.
James Watson and Francis Crick discovered the molecular structure of DNA. In 1953 they designed the double helix model and made it known to the world in April of 1953.