Anton Paul Stadler (28 June 1753 in Bruck an der Leitha – 15 June 1812 in Vienna) was an Austrian clarinet and basset horn player for whom Wolfgang Amadeus Mozart wrote, amongst others, both his Clarinet Quintet (K 581) and Clarinet Concerto (K 622). Stadler's name is inextricably linked to Mozart's compositions for these two instruments. Source : Wikipedia