suspicious person; suspicious character
Refers to a person whose behavior or presence seems questionable, often used in security or police contexts.
The police received a report that a suspicious person was spotted at the station.
I got scared when I saw a suspicious character lurking around late at night.
不審者 is a more common and slightly broader term for a suspicious person, while 不審人物 sounds a bit more formal or official.
Compound of 不審 (suspicion, doubt) and 人物 (person, character).