Guido Hugo Marx (29 March 1871 - 10 September 1949) was an American mechanical engineer who was active in progressive politics, the technocracy movement, and civil liberties. He contributed to helping feed and house hundreds of the 1906 San Francisco earthquake survivors and led the Stanford Academic Council through changes in academic freedom, culminating in founding both the American Association of University Professors and the California chapter of the American Civil Liberties Union.