In the sentence "the bear was killed by the hunter," The topicalized goal of the action ("the bear") is the grammatical subject of the passive sentence and is acted upon by the agent ("the hunter"), which is the logical, but not the grammatical, subject of the passive sentence.
a term (as a noun or pronoun) in a sentence that occupies the position of the subject in normal English word order and anticipates a subsequent word or phrase that specifies the actual substantive content.