What term describes a person who presents someone else's work as their own?

The term that accurately describes a person who presents someone else's work as their own is "plagiarist." This label specifically denotes someone who takes credit for the intellectual property of others without appropriate acknowledgment or permission, effectively passing off that material as their own original work. Plagiarism is a serious ethical violation in academia, the arts, and various professional fields.

In contrast, the other terms do not carry the same implication of dishonesty regarding authorship. An imitator refers to someone who copies the style or actions of another, but this does not necessarily imply fraudulence or misrepresentation. An advocate is someone who supports or argues for a cause or policy, and does not imply any form of misrepresentation. A contributor is a person who adds to a collective effort, which also does not suggest taking credit for someone else's work. Thus, "plagiarist" is the most precise term for someone who misappropriates authorship in this context.