Antonie van Leeuwenhoek (jan 1, 1632 – jan 1, 1723)
Throughout his life, Antonie van Leeuwenhoek invented new microscope lenses that were more advanced and this allowed him to discover protozoa cells when looking at a plaque on peoples teeth. He also discovered single cell organisms and he called these animalcules.
Added to timeline:
A history of the discovery and findings of cells