redoubtable (adj.)

• appalling
• astounding
• awe-inspiring
• awesome
• awful
• celebrated
• dire
• direful
• distinguished
• dread
• dreaded
• dreadful
• eminent
• famed
• fell
• formidable
• frightful
• ghastly
• ghoulish
• great
• grim
• grisly
• gruesome
• hideous
• horrendous
• horrible
• horrid
• horrific
• horrifying
• illustrious
• macabre
• morbid
• notable
• prominent
• renowned
• shocking
• terrible
• terrific
• tremendous