Billy Wilder wrote or co-wrote everything he directed, which is why the dialogue is the reason to watch. He fled Berlin in 1933, worked his way into Hollywood without English, and became one of its sharpest writers within a decade. The scripts move at speed and the jokes carry information.
The range is unusual. Double Indemnity and Sunset Boulevard are corrosive noir, Some Like It Hot and The Apartment are comedies that keep turning cruel, and Stalag 17 and Ace in the Hole are studies in how people behave badly under observation. The Apartment won Best Picture, Director and Screenplay in the same year.
His writing partnerships, first with Charles Brackett and later with I A L Diamond, produced the bulk of the work. Wilder maintained that the third act was the only thing that mattered, and his are unusually hard to see coming.