wer denn

who, then?

→ wer
phrase Uncommon #16,794
who, then? “Denn” adds emphasis or curiosity to the question; its exact effect depends on context.
GE: Wer denn kommt heute mit?
EN: Who, then, is coming along today?

Oh, aufregend, wer denn?

Oh, exciting, who is it?

— David Copperfield - Einmal Reichtum und zurück (2019)

Wer denn gemeinsam?

Who, exactly, is doing it together?

— A Chinese Ghost Story (1987)

Aber wer denn?

But who, then?

— Never Look Away (2018)

Na, wer denn?

Well, who then?

— The Blue Angel (1930)

Wer denn dann?

Who, then?

— Von ganzem Herzen (1998)

Wer denn?

Who then?

— Blow Out - Der Tod löscht alle Spuren (1981)