Karl Ernst Adolf Anderssen (July 6, 1818 – March 13, 1879) was a German chess master. He won the great international tournaments of 1851 and 1862, but lost matches to Paul Morphy in 1858, and to Wilhelm Steinitz in 1866. Accordingly, he is generally regarded as having been the world's leading chess player from 1851 to 1858, and leading active player from 1862 to 1866, although the title of World Chess Champion did not yet exist.