Face Monsters for the horrible sound, definitely. When I first started 1.2.4 I had my volume up high, so when I flew over the just freaked out.
When the DG had its roar, it was the best. Nothing beats Re-Logic level "U JUST GOT TROLL'D!" noise.
As for sprite, definitely Black Recluses are the worst.
And of course for the "I'm-so-screwed" feeling, nothing beats the Dungeon mages.
There's the lava childrenWould be amazing if Terraria get some cool creepypastas, I wonder if the devs've hidden something nasty in the code.
Wat is that guy?There's the lava children
HuehueWat is that guy?
How is it even called?