Succubus from Merriam Webster
Definition:
a demon assuming female form in order to have sexual intercourse with men in their sleep
About the Word:
A succubus is the female version of an incubus – a demon in male form who has sexual intercourse with sleeping females.
Originating in medieval European folklore, with similar beings in many cultures, succubi appear in modern fiction, video games, and South Park.
As a more practical insult, the word is also used figuratively, as in this Jezebel.com headline: “This Week In Tabloids: Courtney the Evil Succubus Maneater Will Devour Bachelor Ben.”
Dictionary.com
/ˈsʌkjʊbəs/
noun (pl) -bi (-ˌbaɪ)
1.
Also called succuba. a female demon fabled to have sexualintercourse with sleeping men Compare incubus
2.
any evil demon
Word Origin
C16: from Medieval Latin, from Late Latin succuba harlot, from Latin succubāre to lie beneath, from sub- + cubāre to lie
How my heart sings 
Most people would know – or be familiar with – ‘incubus’. Not many would know its opposite. Splendid choice. 😉