Three Billy Goats Gruff
On the way to the Hag Rock Redoubt, just south of Markath, you'll find a bridge crossing a river, beside a waterfall. If it's your first time visiting, you'll find two goats running across the bridge to meet a third. Check beneath the bridge, and you'll spot a dead troll.
It's a clever reference to the old Norweigan fairy tale, Three Billy Goats Gruff, in which a trio of goats outsmart a troll who lives under a bridge.