1951 Adult Novel Doubleday (Serialized in Galaxy, 1951)

The Puppet Masters

Definitive alien invasion classic

Narrative Synopsis

Flying-saucer reports in rural Iowa lead secret agent Sam Cavanaugh and his intelligence director father, the "Old Man", to discover that slug-like alien parasites from Titan are riding human spine columns, controlling their hosts with absolute telepathic authority while quietly spreading through American society and government.

Intelligence is the ability to adapt to change. If you can't adapt, you become lunch or a draft horse.
Notable Passage

Historical & Editorial Context

A cornerstone of 1950s invasion literature, predating Invasion of the Body Snatchers and establishing the modern alien parasite trope.