calumniator
cynic
defamer
derogator
libel
mudslinger
slander
slanderer
vilifier
fault-finder
backbiter
hatemonger
libeler
maligner
muckraker
traducer
calumny
censurer
cold-bloodedness
disturber
grumbler
litigant
tempter
votary
actor
compactor
factor
reactor
refractor
tractor
proponent
supporter