Frankenstein's monster
Something that harms or destroys its creator and cannot be controlled. A reference to the monster in the book Frankenstein by Mary Shelley. At first, my side business seemed like a good idea, but it has turned into Frankenstein's monster, eating away at my time and finances.
Frankenstein's monster
a thing that becomes terrifying or destructive to its maker. Frankenstein was the title of a novel written in 1818 by Mary Shelley . The scientist Frankenstein creates and brings to life a manlike monster which eventually turns on him and destroys him; Frankenstein is not the name of the monster itself, as is often assumed.
1991 John Kingdom Local Government & Politics in Britain The factories of the bourgeoisie had created another dangerous by-product, a Frankenstein's monster posing a constant sense of threat—the working class.