Karl Ernst Adolf Anderssen was a German chess master. He is considered to have been the world's leading chess player for much of the 1850s and 1860s. He was quite soundly defeated by Paul Morphy who toured Europe in 1858, but Morphy retired from chess soon after and Anderssen was again considered the leading player.
After his defeat by Steinitz in 1866, Anderssen became the most successful tournament player in Europe, winning over half the events he entered—including the Baden-Baden 1870 chess tournament, one of the strongest tournaments of the era. He achieved most of these successes when he was over the age of 50.
Anderssen is famous even today for his brilliant sacrificial attacking play, particularly in the "Immortal Game" (1851) and the "Evergreen Game" (1852). He was a very important figure in the development of chess problems, driving forward the transition from the "Old School" of problem composition to the elegance and complexity of modern compositions.
He was also one of the most likeable of chess masters and became an "elder statesman" of the game, to whom others turned for advice or arbitration.