misaligner
misperceiver
misapplier
misplacer
mislabeler
misstater
misconstruer
mislayer
misdealer
misdescriber
misidentifier
misunderstander
misreader
misconceiver
misteacher
misguider
misbehaver
belittler
misdirector
misspeaker
misreporter
misjudger
mismanager
misrepresenter
misinformer
obscurant
misfirer
misappropriator
miseducator
mispronouncer
would lose one's head if it wasn't attached
dishonourer
mishandler
discreditor
discommender
misnamer
mishearer
undeceiver
noncomprehender
underpredictor
misshaper
disinformant
foister
disinformer
confounder
deludee
refounder
contorter
disannuller
inciter