redoubtable

Short definition from Wiktionary

Adjective

1. 1
   Especially of a person: Eliciting respect; awe-inspiring, imposing.
2. 2
   Especially of a person: Eliciting dread or fear; appalling, formidable.

Noun

1. 1
   A person who elicits respect.
2. 2
   A person who elicits dread or fear; a formidable person.