Philipp Bouhler (11 September 1899 – 19 May 1945) was a German senior Nazi Party functionary who was both a Reichsleiter (National Leader) and Chief of the Chancellery of the Führer of the NSDAP.

[6] Historian Ian Kershaw avows that because Hitler paid "little attention to administration and organization", he relied on the "indefatigable and subservient" yet "inwardly ambitious" Bouhler and other Party bosses like him.

[7] According historian Klaus Fischer, the "owlish looking" Bouhler was part of Adolf Hitler's early inner circle and as a "diffident and punctilious bureaucrat", the Führer could trust him to "carry out any order, no matter how outlandish".

[13][a] Meanwhile, Bouhler was also able to get Hitler to sign the document authorizing the euthanasia program itself and while not possessing the force of law, it provided the necessary protection to get once reluctant physicians to participate.

Brandt are charged with the responsibility of enlarging the competence of certain physicians, designated by name, so that patients who, on the basis of human judgment, are considered incurable, can be granted mercy death after a discerning diagnosis.

[20] For adults destined for euthanasia, Bouhler and Brandt established "secret-service-style" operations at the Tiergartenstrasse 4 (from whence the program acquired its name) location in Berlin, disguising the murders as medical procedures.

[21] Aside from securing the authorization for the T4 Program and overseeing it, when the plans to ship all of Europe's Jewish population to Madagascar was being proposed during the summer of 1940, Bouhler was designated as the East African colony's future governor.

[6] Propaganda minister, Joseph Goebbels was opposed to this writ-large authority granted to Bouhler over all books, a concern he expressed in a personal diary entry from June 1941.

[24] Bouhler's office was responsible for Hitler's correspondence, which included private and internal communications as well as responding to public inquiries (for example, requests for material help, godfathership, jobs, clemency, NSDAP business, and birthday wishes).

By order of Hitler (backdated to 1 September 1939), Bouhler with Karl Brandt developed the Nazis' early euthanasia program, Aktion T4 in which mentally ill, developmentally, and physically disabled people were killed.

[29] Additional euthanasia facilities were established at Bernburg, Grafeneck, Brandenburg, Sonnenstein, and Hadamar between 1940 and 1941,[30] where approximately 70,000 people were murdered in gas chambers using carbon-monoxide.