How many letters does the top answer for “wrote the 120 days of sodom” have?

The most common answer is sade (4 letters).

Crossword clue: wrote the 120 days of sodom

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

sade 4 letters wd-fact-v3

French soldier and writer whose descriptions of sexual perversion gave rise to the term `sadism' (1740-1814)

author of the 120 days of sodom 50% similar → sade

wrote burmese days 50% similar → orwell

wrote night and day 50% similar → porter

wrote the ancient of days 50% similar → blake

wrote the day of the jackal 50% similar → zinnemann

wrote the five days 50% similar → argento

wrote the remains of the day 50% similar → ishiguro