Biographer (noun)

A person who writes the biography of someone else.

Origin:

Late 18th century; earliest use found in the monthly review. from bio- + -graph + -er.

Examples:

1. She became a famous biographer after writing a book about a president.
2. He is a biographer of famous actors.
3. The biographer spent years researching the subject's life.
4. The biographer interviewed many people who knew the subject.
5. The subject's family cooperated with the biographer.