instigator

verb (used with object), in·sti·gat·ed, in·sti·gat·ing.

1. to cause by incitement; foment: to instigate a quarrel.
2. to urge, provoke, or incite to some action or course: to instigate the people to revolt.

verb (tr)

1. to bring about, as by incitement or urgingto instigate rebellion
2. to urge on to some drastic or inadvisable action

n.

1590s, from Latin instigator, agent noun from instigare (see instigation). Fem. formation instigatrix is recorded from 1610s.

v.

1540s, back-formation from instigation or else from Latin instigatus, past participle of instigare “to urge on, incite” (see instigation). Related: Instigated; instigates; instigating.