How many letters does the top answer for “author of world war z” have?

The most common answer is brooks (6 letters).

Crossword clue: author of world war z

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

brooks 6 letters wd-fact-v3

United States literary critic and historian (1886-1963)

author of the war of the worlds 75% similar → wells

wrote world war z 60% similar → brooks

author of on war 50% similar → clausewitz