How many letters does the top answer for “in which game did the character mario make his first appearance” have?

The most common answer is donkey (6 letters).

Crossword clue: in which game did the character mario make his first appearance

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

donkey 6 letters otdb

domestic beast of burden descended from the African wild ass; patient but stubborn

kong 4 letters otdb