The only enemies I ever thought were scary were Zant's Hands and the Shadow Beasts. At first, you think that they turn the people they kill into Shadow Beasts, just like themselves. And their howl is a lot freakier than the Redeads'.

Zant's Hands are self explanatory.

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I am not going to be on this site for about a month (not that it matters much) until I get Spirit Tracks and beat it. (I don't want the plot spoiled, after all.) But I'll be back!