pacificator
/pəˈsɪfɪkeɪtə/noun
A person who or thing which pacificates someone or something; a peacemaker; a thing that soothes or subdues.
Origin
Mid 16th century; earliest use found in Thomas Cromwell (d. 1540), royal minister. From classical Latin pācificātor peacemaker, pacifier from pācificāt-, past participial stem of pācificāre + -or. Compare Middle French, French pacificateur arbiter, peacemaker.