agent provocateur
agitator
agitprop
catalyst
complainer
demagogue
exciter
firebrand
fomenter
gadfly
hooligan
incendiary
inciter
inflamer
instigator
malcontent
meddler
mischief-maker
provocateur
provoker
rabble-rouser
ringleader
rouser
scandalmonger
seditionary
seditionist
stirrer
stormy petrel
urger
persona non grata
unwelcome person
Heller
badgerer
blusterer
cut-up
devil
disturber
heckler
hellhound
hellion
hoaxer
instigant
loud-mouth
practical joker
prankster
rioter
tricker
trickster
aggressor
blackmailer
coxcombs
dissident
egoist
faker
miscreants
mutineer
poisoner
rednecks
riffraff
seedship
sympathizer
to-day