Emil Christian Hansen (May 8, 1842 - August 27, 1909) was a Danish fermentation physiologist.

He financed his education by writing novels and he was awarded a gold medal in 1876 for an essay on fungi.

Employed by the Carlsberg Laboratories in Copenhagen, he made the important discovery that yeast was composed of different kinds of fungi and that the yeast culture could be cultivated. He isolated a pure cell of yeast and, combining it with a sugary solution, produced more yeast than was in a yeast bank. It was known as Saccharomyces Carlsbergensis , and is used in lager beers. See Fermentation, Yeast.

Even Pasteur admired Hansen's work.