The phrase "mysterious outsider" refers to someone who is not well-known or understood by others and who seems to possess a sense of secrecy or intrigue. Full definition
Director Tim Burton has long trafficked in stories about mysterious outsiders who have strange abilities that lead them to great (and often pretty scary) things, all in service to some major cinematic achievements. (indiewire.com)
It's a spritely, dark and mischievous film, part home invasion thriller, part fairy tale as a chimeric and mysterious outsider inveigles his way into an affluent suburban home and things gradually turn murderous as he Pied - Pipers himself into the family structure. (indiewire.com)
Along the way, she teams with a mysterious government agent, played by Josh Brolin, and an even more mysterious outsider, played by Benicio Del Toro. (slashfilm.com)