Austrian born American film maker who won three Academy Awards for the apartment?

You're thinking of Billy Wilder, an Austrian-born American filmmaker. He won three Academy Awards for *The Apartment* in 1960:

* Best Director

* Best Screenplay Written Directly for the Screen (shared with I.A.L. Diamond)

* Best Picture

He was also nominated for Best Actor for his role in *The Lost Weekend* (1945), but did not win.