Listening to an episode of Wait, Wait, Don’t Tell Me on NPR (National Public Radio), I was surprised to hear a reference to Svengali not once, but twice.
So-and-so is a “steroid Svengali”
Liberace was “a controlling Svengali”
My mother was apt to call a person “a Svengali,” and I’ve used the word in my own writing, but I wasn’t aware that a younger generation was still using the term. A Google search brings up plenty more examples:
Kimberly Vertolli said that she will not advocate for her ex in his Senate run because she fears he is too influenced by a Svengali figure in his life…
“Ordinary People View Rush [Limbaugh] as a Dangerous Svengali
Mike Danton, David Frost, And The Return Of The Unkillable Hockey Svengali
Rahm Emanuel: Ardent Zionist called Obama Svengali
former Bush administration svengali Karl Rove
Malcolm McLaren, the Svengali of Punk, died Yesterday aged 64.

Svengali is an eponym (word that comes from a person’s name) that means “a person who exercises a controlling or hypnotic influence on another, frequently for evil ends.”
The word derives from the name of a character in the 19th century gothic novel Trilby (1894), written by George du Maurier (1834-1896). In the novel, Svengali is an evil hypnotist who enables an untalented young woman named Trilby to become a great singer.