grudge :

a feeling of dislike for someone because you cannot forget that they harmed you in the past

"Is there anyone who might have had a grudge against her?"
"Mr Gillis was not normally a man to bear grudges ."
"I'm not harbouring some secret grudge against you."
"It could be the work of someone with a grudge against the company."
"You let nasty little personal grudges creep in."