Select the most appropriate one-word substitution for the given group of words. 

A signature of a celebrity (signature of oneself) 

Autograph

The most appropriate one-word substitution for the given group of words is autograph.

• Autobiography is a person's own life story, written by themselves.
• Biography is a person's life story, written by someone else.
• Signature is a person's handwritten name or mark, used to sign documents or other items.
• Autograph is a signature of a celebrity or other famous person.