The first scientist to study cells was Robert Hooke. In 1665, he used a microscope to observe thin slices of cork and noticed small, box-like compartments, which he named "cells" because they reminded him of the cells of a monastery.

However, it's important to note that Hooke only observed the cell walls of dead plant cells. The discovery of living cells was made later by Anton van Leeuwenhoek, who used his own microscopes to observe tiny organisms in pond water and blood.

So, while Hooke is credited with the first observations of cells, Leeuwenhoek was the first to observe living cells.