menacing,
minacious,
minatory,
baleful,
forbidding,
ominous,
threatening,
sinister threatening or foreshadowing evil or tragic developments; "a baleful look"; "forbidding thunderclouds"; "his tone became menacing"; "ominous rumblings of discontent"; "sinister storm clouds"; "a sinister smile"; "his threatening behavior"; "ugly black clouds"; "the situation became ugly"
creepy-crawly,
creepy causing a sensation as of things crawling on your skin; "a creepy story"; "I had a creepy-crawly feeling"
unnerving,
formidable,
redoubtable inspiring fear; "the formidable prospect of major surgery"; "a tougher and more redoubtable adversary than the heel-clicking, jackbooted fanatic"- G.H.Johnston; "something unnerving and prisonlike about high grey wall"
grisly,
gruesome,
macabre,
ghastly,
grim,
sick shockingly repellent; inspiring horror; "ghastly wounds"; "the grim aftermath of the bombing"; "the grim task of burying the victims"; "a grisly murder"; "gruesome evidence of human sacrifice"; "macabre tales of war and plague in the Middle ages"; "macabre tortures conceived by madmen"
hairy hazardous and frightening; "hairy moments in the mountains"
