pathfinder 2e – What would be some good monsters to stalk the party like the Nemesis in Resident Evil?

As the question states, I’m looking for a monster that can stalk the party for the latter half of a campaign I’m running. They are only level 3-4 so it would have to be something way too strong to fight head on but preferably slow or stupid or both so they have the chance to escape it. I of course plan for them to be able to slay this monster once they gain 7-10 levels.