Louis Paulsen

Louis Paulsen (15 January 1833, Gut Nassengrund near Blomberg, Principality of Lippe – 18 August 1891) was a German chess player.

In the 1860s and 1870s, he was among the top five players in the world. He was a younger brother of Wilfried Paulsen.

Paulsen was one of the first players to challenge the notion that an attack could be constructed out of brilliance. He put forward the idea that any brilliant attack would have failed against correct defence. His ideas were grasped by Wilhelm Steinitz, who declared that attack and defence have equal status, and particularly by Aron Nimzowitsch, who listed Paulsen among his six greatest "purely defensive players". Paul Morphy and Paulsen were early masters of the game and of blindfold chess; they were capable of playing 10 blindfold games at the same time without any major errors. In 1862 Paulsen challenged Adolf Anderssen for the world championship. The eight-game match was a tie and Anderssen remained an unofficial world champion. Paulsen defeated Anderssen in matches in 1876 and 1877.

Paulsen has many contributions in the opening theory such as the Sicilian Dragon, the Sicilian Paulsen variation, French Defense Paulsen Attack and Vienne Game Paulsen variation.