Answer:

TROLL

Answer	Crossword Clue
TROLL	Under-bridge dweller of myth
TROLL	Folk tale creature
TROLL	Fish, in a way

TROLL	Northern gnome
TROLL	Mythical monster
TROLL	Being under a bridge
TROLL	Fairy-tale monster
TROLL	1960s fad doll
TROLL	Internet-forum rabble-rouser
TROLL	Online agitator
TROLL	Bridge monster

TROLL	Baddie under a bridge
TROLL	"... the ancient Yuletide carol ..."
TROLL	Fish with a moving line
TROLL	Ogre cousin
TROLL	Fairy-tale toll collector
TROLL	Mythical cave dweller
TROLL	Underground folklore creature
TROLL	Faddish long-haired collectible doll

TROLL	Billy Goats Gruff menacer
TROLL	Fairy tale lurker
TROLL	Fairy tale threat
TROLL	Under-the-bridge folklore villain
TROLL	Fad toy of the '90s
TROLL	Faddish long-haired doll
TROLL	Dwarf of folklore
TROLL	Gnomelike character

TROLL	Newsgroup troublemaker
TROLL	Long-haired doll
TROLL	Doll with spiky bright hair
TROLL	Fad doll with spiky hair
TROLL	Leprechaun kin
TROLL	Creature fought by Harry Potter
TROLL	Fish from the stern
TROLL	Fairy tale creature

TROLL	Cave dweller of folklore
TROLL	Fairy tale character
TROLL	Internet forum troublemaker
TROLL	"The Three Billy Goats Gruff" meanie
TROLL	On-line instigator