How many letters does the top answer for “author of sunset boulevard” have?

The most common answer is stroheim (8 letters).

Crossword clue: author of sunset boulevard

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

stroheim 8 letters wd-fact-v3

wilder 6 letters wd-fact-v3

United States filmmaker (born in Austria) whose dark humor infused many of the films he made (1906-2002)

director of sunset boulevard 50% similar → stroheim

wrote sunset boulevard 50% similar → stroheim, wilder