Here’s an idea for a dungeon encounter to frighten, or at least annoy the players.
Coming towards them down a corridor, the adventurers see a robed, skeletal figure holding a scythe, reaching out to them. If they flee, they soon see the figure again, coming down a different corridor towards them. The creature can be avoided at top speed, but it always comes back. Missiles and spells thrown at it do nothing. It does not speak, but its eyes do glow a glaring gold.
When the creature finally catches up to the adventurers, they discover that the figure is not Death, but rather his cousin, Taxes. The figure demands a percentage of their treasure, hands them a receipt, and then goes quietly back into the shadows.