Paul Langerhans was a German pathologist and anatomist born on June 25, 1847. He is best known for discovering the Langerhans cells, which are specialized immune cells found in the skin. His work contributed significantly to the understanding of the immune system and its functions. In addition to his discovery of Langerhans cells, he also identified the Langerhans islets in the pancreas, which play a crucial role in regulating blood sugar levels. Langerhans' research laid the groundwork for future studies in both immunology and endocrinology, making him a notable figure in medical history.