Answer:

troll

Answer	Crossword Clue
TROLL	Online provocateur
TROLL	Online troublemaker
TROLL	Forum troublemaker

TROLL	Provocative poster
TROLL	Online instigator
TROLL	Nuisance in an online comments section
TROLL	Offensive poster
TROLL	See 39-Down
TROLL	Onetime fad doll
TROLL	Fairy tale figure
TROLL	Sing the parts of in succession

TROLL	Internet forum menace
TROLL	Internet forum rabble-rouser
TROLL	Fairy tale character
TROLL	Sing
TROLL	Bridge enthusiast?
TROLL	Fish in a way
TROLL	Creature under a bridge
TROLL	Cave-dweller

TROLL	Bridge guardian
TROLL	One way to fish
TROLL	Folklore dwarf
TROLL	Fad doll of the '90s
TROLL	Cave dweller
TROLL	Fairy tale villain