adapter for film or stage; dramatizer
Refers to a person who adapts a story, novel, or other work into a screenplay or stage script. The term is somewhat specialized and less common in everyday conversation.
He is credited as the adapter of that novel.
The adapter skillfully brought the atmosphere of the original work into the script.
脚色 is the act of adapting or dramatizing; 脚色者 is the person who does it.
Compound of 脚色 (adaptation for stage or screen) and 者 (person). The exact historical derivation of 脚色 is uncertain, but it is conventionally associated with the meaning of adapting a story.