SHILL:
1. a person who poses as a customer in order to decoy others into participating, as at a gambling house, auction, confidence game, etc.
2. a person who publicizes or praises something or someone for reasons of self-interest, personal profit, or friendship or loyalty.
And from MERRIAM-WEBSTER:
1 a: one who acts as a decoy (as for a pitchman or gambler) b: one who makes a sales pitch or serves as a promoter
"Jaws is the Citizen Kane of movies."
blocked: logan2, Diamonds3, Hamilton22