Michèl Yost (Paris, 1754 ? Paris, July 5, 1786) was a famous French clarinetist and cofounder of the French clarinet school. He was a brilliant instrumentalist and even known beyond the boundaries of France.
Joseph Beer (1744?1811) was Yost's teacher. Yost himself was a clarinet teacher counting famous clarinetists such as Xavier Lefèvre amongst his pupils.
Source : Wikipedia