Svengali

Sven·ga·li n. pl. Sven·ga·lis

1: A person who, with evil intent, tries to persuade another to do what is desired:

“a crafty Svengali who lures talented people with grand promises yet gives them little lasting operational authority” (Chris Welles).

2: someone (usually maleficent) who tries to persuade or force another person to do his bidding

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3: the musician in the novel, Trilby, by George du Maurier who controls Trilby's singing hypnotically