Karl Landsteiner

Karl Landsteiner was an Austrian immunologist and pathologist, best known for discovering the human blood groups in 1900. His work identified the ABO blood group system, classifying blood into four types (A, B, AB, and O), which is crucial for safe blood transfusions. Landsteiner's research laid the groundwork for modern blood transfusion medicine and improved patient care significantly. He was awarded the Nobel Prize in Physiology or Medicine in 1930 for his contributions to immunology. His discoveries remain vital in medical science and have saved countless lives.