...but the hero can and does blame the villain or he was lying and the hero finds out.
Two families feud across several generations because of this trope, but have forgotten why it even began.
The hero is hunting the villain to revenge somebody who's only vaguely related to him. "You killed my father's cousin's mother's sister's daughter's son's third wife's roommate!"
The hero hunts the person who killed his goldfish.
The slight is even more comically petty: "You stole my sandwiches!"
His father's ghost comes back to tell him to get revenge on his killers. He died of a heart attack.
"You killed my father!" "No, I am your father!" "What, seriously?" "Yes. You see — *UGGH*!" "What, where'd that knife come from?!" "Me, and he's not your real father!" "How would you know?" "Because I KILLED YOUR FATHER!" "Meh, I never liked the old bastard anyway."
The Hero wants to kill the villain to avenge his father. Another person beats him to it though and kills the villain. It is later discovered that the man who killed the villain is the hero's long lost brother and he killed the villain to avenge their father.
The hero's father is alive, or died of causes unrelated to the villain.
The hero's father was killed by the villain, but doesn't believe in revenge and has other reasons to try and defeat the villain.
The hero remains unaware of who killed his/her father through the story.