noun
A person who believes that all events are predetermined and inevitable; a philosophical term.
彼は運命は変えられないと考えるフェータリストだ。
He is a fatalist who believes that fate cannot be changed.
決定論者 is a more formal term for a determinist, often used in philosophical contexts, while フェータリスト is a direct loanword with a slightly more literary or personal nuance.
Loanword from English 'fatalist'.