Spiders of Mirkwood

In particular, their depiction from the 1977 Rankin/Bass adaptation of Tolkien's The Hobbit.

For the most part, these spiders are pretty typical, both visually and plot-wise, although they do have the power of speech. Two things really set them apart from all other depictions, and other spider-themed monsters. First, their faces:

An utterly bizarre mix of goofy and creepy, the face seems to be an exaggeration of a real spider's, the fangs forming a beard and pedipalps become bunny ears. 

The other curious aspect is their death. Every time a spider is killed, the screen 'freezes' the image of the dead spider, fractures, and spins wildly, exactly like a kaleidoscope!

The first spider pulls an incredibly terrifying expression upon being killed. A few of the others have similar expressions, but aren't anywhere near as extreme.

You'd think this would be an "attack" face, but it's quite the opposite.