How many letters does the top answer for “author of interview with the vampire” have?

The most common answer is rice (4 letters).

Crossword clue: author of interview with the vampire

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

rice 4 letters wd-fact-v3

grains used as food either unpolished or more often polished

author of vampires 67% similar → carpenter

author of the vampire diaries 50% similar → smith

wrote interview with the vampire 50% similar → rice