Refers to the person who carries out an action, often in legal, ethical, or formal contexts. Can be neutral or negative depending on the deed.
The perpetrator of the crime has not yet been identified.
Who is the doer of this plan?
実行者 emphasizes the actual execution or implementation of a plan, whereas 行為者 focuses on the general concept of being the actor.
Compound of 行為 (action, deed) and 者 (person). A straightforward Sino-Japanese formation.