Answer:

hisser

Answer	Crossword Clue
HISSER	One showing contempt
HISSER	Disapproving one
HISSER	Snake, on occasion

HISSER	Snake, at times
HISSER	Curtain-call critic
HISSER	Bane of an off-key tenor
HISSER	One who expresses contempt
HISSER	Cat, at times
HISSER	Many a snake
HISSER	Snake or cat, on occasion
HISSER	An obviously angry snake or cat

HISSER	He greets the villain