alarming
bloodcurdling
frightening
grim
grisly
gruesome
hair-raising
hideous
horrible
horrid
horrifying
macabre
paralyzing
petrifying
scary
shocking
stunning
stupefying
terrible
terror
terror-bearing
terror-breathing
terror-breeding
terror-bringing
terror-fraught
terror-giving
terror-inspiring
terror-striking
terrorful
terroristic
terrify
clarifying
verifying