How many letters does the top answer for “wrote the star rover” have?

The most common answer is london (6 letters).

Crossword clue: wrote the star rover

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

london 6 letters wd-fact-v3

the capital and largest city of England; located on the Thames in southeastern England; financial and industrial and cul

author of the star rover 50% similar → london

wrote a star is born 50% similar → streisand

wrote double star 50% similar → heinlein

wrote star maker 50% similar → stapledon

wrote star trek 50% similar → roddenberry

wrote star wars 50% similar → hamill, lucas