Synonyms that are in the dictionary are marked in green. Synonyms that are not in the dictionary are marked in red.
Antonyms that are in the dictionary are marked in green. Antonyms that are not in the dictionary are marked in red.
The literal answer to the question of who killed Harlan Thrombey is that he killed himself, cutting his own throat with a knife.
Source: https://screenrant.com/knives-out-movie-ending-explained-killer-chris-evans/