A speaker or narrator — a person who speaks or tells a story (e.g., in a speech or narration).
講演会の話者は著名な研究者だった。
The speaker at the lecture was a well-known researcher.
小説の話者の視点が作品の印象を左右する。
The narrator's perspective in a novel affects the overall impression of the work.
会場の話者がマイクを使って自己紹介した。
The speaker at the venue used the microphone to introduce themselves.
A speaker of a language — a person who speaks a particular language (e.g., a native speaker).
彼は英語の話者だが、日本語も日常会話は問題ない。
He is an English speaker, but his Japanese is also fine for daily conversation.
母語話者（ぼごわしゃ）はその言語の自然な運用に長けている。
A native speaker is adept at using that language naturally.