allusive use for man-made monsters dates to 1838, from Baron Frankenstein, character in Mary Shelley's 1818 novel "Frankenstein: The Modern Prometheus." Commonly taken (mistakenly) as the proper name of the monster, not the creator, and thus franken- extended 1990s as a prefix to mean "non-natural." The German surname is probably literally "Franconian Mountain," stein being used especially for steep, rocky peaks, which in the Rhineland often were crowned with castles. The Shelleys might have passed one in their travels. The German surname also suggests "free stone."
Frankenstein is the creator-victim; the creature-despot & fatal creation is Frankenstein's monster. The blunder is very common indeed -- almost, but surely not quite, sanctioned by custom. [Fowler]