Microbes weren't "invented" in the sense of being created. They have existed for billions of years, long before humans were around.

However, we can say that Anton van Leeuwenhoek is credited with discovering microbes. He was a Dutch scientist who, in the 17th century, used his own crafted microscopes to observe tiny living organisms in water, which he called "animalcules".

While Leeuwenhoek didn't understand the full significance of his discovery, it marked the beginning of our understanding of the microbial world. His work laid the foundation for future microbiologists to study, classify, and ultimately understand the vast diversity and importance of microbes in our world.