The first person to observe living cells under a microscope was Anton van Leeuwenhoek in the 17th century. He was a Dutch scientist and businessman who is known as the "Father of Microbiology".

While Robert Hooke first observed cells in 1665, he was looking at the dead cells of cork. Leeuwenhoek, on the other hand, observed living cells in pond water and other samples. He even described the movement of single-celled organisms like bacteria, which he called "animalcules".