Have 你 seen...?

Have 你 seen people before that were so strange in behavior and looks that 你 knew beyond a reasonable doubt they were an alien?

I have. I would go up to this super market almost every night to visit my friend that was a security guard. Every 3 nights this guy would come in and get the same thing every time. It was some kind of crackers. He wouldn't speak to anyone. He always had this blank face, like he had no personality almost alien. he would walk weird as well. I've met people with no personality, but it was just different and strange.