Conrad Schlumberger (2 October 1878 in Guebwiller – 9 May 1936 in Stockholm) and Marcel Schlumberger (21 June 1884 in Guebwiller – 9 May 1953 in Val-Richer) were brothers from the Alsace region of the German Empire in what is now modern France. Their inventions in the area of geophysics and well logging were the beginnings of Schlumberger Well Services and the entire well logging industry.