evil genius
noun
1A malevolent spirit imagined as accompanying a person and seeking to influence him or her to do evil, and often paired with an opposed benevolent spirit; (in extended use) a person who exerts an evil influence; compare genius, malus genius.
2A person with an exceptional capacity for wrongdoing or malevolence.
Origin
Late 17th century; earliest use found in Afra Behn (?1640–1689), writer.