Answer: grimmest

AnswerCrossword Clue
grimmestDepressing or worrying to consider
grimmest(of humor) Lacking genuine levity; mirthless; black
grimmestUnrelentingly harsh; merciless or severe
grimmestForbidding or uninviting
grimmestGRIM, stern and unrelenting
grimmestAllowing no compromise; stern; relentless