Why is Louis Pasteur famous?

Louis Pasteur was a French biochemist who, among other things, discovered pasteurization of milk and made contributions to the Germ Theory. He was trained as a chemist but was NOT a Medical Doctor. The term "vaccination" was also coined by him, the term being derived from the French word for Cow (la vache).

(It should be noted that even Neolithic cave men recognized that cooking was used in processing food and in effect, killed germs, centuries before Pasteur.)