Who's there?

Who's there?

 and Who is it?
a question asking who is on the other side of a door or concealed in some other place. Hearing a noise, Tom called out in the darkness, "Who's there?" Hearing a knock on the door, Mary went to the door and said, "Who is it?"
References in periodicals archive ?
DoorStop X is particularly powerful when combined with Open Door's Who's There?
Through August 15, DoorStop X can be purchased off the site for the special introductory price of $39, or $59 when bundled with Who's There?