Marek Jan Siemek (November 27, 1942 – May 30, 2011) was a Polish philosopher and historian of German transcendental philosophy (German idealism). He was a professor at the Institute of Philosophy of the University of Warsaw and the director of its Department of Social Philosophy.^[1]

Marek Siemek was a disciple of Bronisław Baczko, one of the main representatives of the Warsaw School of the History of Ideas. In his early works Siemek interprets marxism as a form of transcendental philosophy. In his later works ha abandons Marxism for hegelianism interpreted as transcendental social philosophy.

From 1986 member of International Advisory Committee of The Internationale Hegel-Gesellschaft. Fellow of Collegium Invisibile.^[2] On 10 February 2006 he received doctorate honoris causa of the University of Bonn.

Marek Siemek had one son, currently residing in the United States.

• Fryderyk Schiller, Warszawa, Wiedza Powszechna, 1970
• Idea transcendentalizmu u Fichtego i Kanta, Warszawa, PWN, 1977
• Filozofia, dialektyka, rzeczywistość, Warszawa, PIW, 1982
• W kręgu filozofów, Warszawa, Czytelnik, 1984
• Filozofia spełnionej nowoczesności - Hegel, Wykłady Kopernikańskie w Humanistyce, vol. 2, Toruń, Wydawnictwo UMK, 1995.
• Hegel i filozofia, Warszawa, Oficyna Naukowa, 1998
• Vernunft und Intersubjektivität. Zur philosophisch-politischen Identität der europäischen Moderne, Baden-Baden, Nomos Verlagsgesellschaft, 2000
• Wolność, rozum, intersubiektywność, Warszawa, Oficyna Naukowa, 2002^[3]