What is the term for a written account of someone's life, authored by someone else?

The correct answer is biography. A biography is specifically defined as a detailed account of a person's life, written by someone who is not the subject of the account. It typically encompasses various aspects of the person's life, including their experiences, achievements, and influences, providing a thorough perspective on their life journey.

In contrast, an autobiography is a self-written account of one's own life, focusing on the author's personal experiences and insights. A memoir is a subset of autobiography that usually emphasizes specific memories or themes rather than covering the subject's entire life. A narrative refers to any form of storytelling that can include various genres and types of accounts, but it does not specifically refer to a life story. Thus, biography is the polished term that accurately captures the essence of a life story written by someone else.