A person who willingly or not takes the blame and punishment for another's misdoings; patsy: He said he would not be the president's fall guy(1906+)
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with fall-guy
A scapegoat, one who is blamed for the actions of others. For example, He refused to be the fall guy for his colleagues. This expression uses fall in the sense of “consequences” or “blame,” which originated in prison slang.
[ ; early 1900s