I.G. Farben was a German Corporation which was closely associated with the National Socialist era in Germany. A chemical producer (which had a monopoly on the Chemicals market in Germany) it was responsible for the production of zyklon B, the gas used in the Death Camps. Tainted by the holocaust the directors were captured by the Allies and tried for a number of war crimes. Of the corporation only BASF, AGFA and Bayer still exist as companies.
Here is an article about their involvement with the regime:
CHAPTER TWO: The Empire of I.G. Farben