He is the first microbiologist and the first to observe microorganisms using a microscope

Antonie van Leeuwenhoek was a Dutch scientist who is considered the first microbiologist. He was the first to observe and describe microorganisms (which he called 'animalcules') using single-lens microscopes of his own design in the 1670s. Albert Einstein and Isaac Newton were physicists, while Gregor Mendel was a geneticist.