grievancer
noun/ˈɡɹiːvənsə(ɹ)/
Etymology From grievance + -er.
1
One who gives grievance, a complainer.
- Petition […] against the bishops as grand grievancers.1655, Thomas Fuller, The Church-history of Britain; […], London: […] Iohn Williams […], →OCLC, (please specify |book=I to XI):