Examples:

• Who is that woman, and what has she done with Daisy?
• Who is that friend that always calls you by phone?
• Who is that guest and why is so important?
• Who is that guy, and what is he so proud of?
• Who is that man in the background of the picture?
• Who is that and why is he waving at us?
• Hold on a minute. Who is that talking to my wife?
• Who is that man, and how does he know me?
• Who is that woman looking at you... from the last row?
• Who is that girl, standing by the door?