1A casual word for a person — “guy,” “fellow,” “the one.” Can be rough, affectionate, or contemptuous depending on tone. The kanji 奴 feels harder and more masculine; the kana form やつ is more neutral.
彼は本当に優しい奴だ。
He's a really kind guy.
いいやつだと思ってたのに、裏切られた。
I thought he was a good guy, but he betrayed me.
お前みたいなやつには負けない。
I won't lose to a guy like you.
鈴木っていうやつ、知ってる？
Do you know a guy named Suzuki?
奴ら、また何か企んでいるな。
Those guys are scheming something again.
2A colloquial word for a thing or object — like “the one” or “that thing.” Very commonly used to single out a particular type or item, e.g., 赤いやつ (the red one), 大きいやつ (the big one).
一番大きいやつをください。
I'll have the biggest one, please.
赤いやつより青いやつのほうが好きだ。
I like the blue one better than the red one.
このパソコン、古いけどけっこういいやつだよ。
This computer's old, but it's actually a pretty good one.
さっき言ってたやつ、もう一回見せてくれない？
Could you show me that thing you mentioned earlier one more time?
3Used as a third-person pronoun meaning “he/she/him/her,” with a rough or masculine tone. Refers without a modifier to someone already known in context (奴は〜, 奴の〜). Most often seen in fiction, manga, and tough-guy dialogue.
奴は約束を必ず守る男だ。
He's a man who always keeps his word.
奴の本当の目的がまだ分からない。
I still don't know what he's really after.
気を付けろ。奴は曲者だぞ。
Watch out — he's a tricky one.