(Common usage) One who creates, manipulates, and performs with puppets
(Slang) A person who willingly or unwillingly manipulates others.
(Science fiction) A race of alien creatures, dreamed up by Larry Niven in his "Known Space" stories. They got their name from the fact that they resemble a pupeteer manipulating several "Cecil the Seasick Sea Snake" puppets. Puppeteers manipulate most objects with their tongues, which humans find somewhat disgusting; not surprisingly, one character finds it repulsive that his puppeteer bartender has fixed him a drink with his mouth.
Ironically (to us, not to Niven), the Puppeteers also have architected major events in human history to serve themslves. This is somewhat odd, as the Puppeteers are notorious cowards, and one would think that they would think twice about pissing off a highly aggressive and successful species.
Cowardice is revered in Puppeteer society; its highest office, equivalent to "President" or "Prime Minister", is the "Hindmost"; the one with most status is the one privileged to take the rear.
Puppeteers are the sole proprietors of the General Products Hull, an indestructible and transparent spacecraft hull, fabricated from a single molecule. Puppeteers, not surprisingly, are also the Galaxy's most tight-fisted sons-of-bitches.