Looking for Specific Poetry

For my senior research paper, I have to use Richard III and compare the rhetoric of Shakespeare and compare it to two other works expressing the same theme. I'm using Richard III and The Scarlet Letter thus far. My teacher/professor loves my ideas and parallels, but I need one more source and he told me to keep going with the Evil guys using a false guise, and also are intentionally given the symbol of an animal.

So...is anyone aware of other pieces of classical literature that express the similar theme? The bad guy uses a fake outward appearance to fool those around him/her and carry out their devious means. I especially wanted to find a character deliberately represented as an animal, as Richard's royal symbol is the boar and Chillingworth refers to Chillingworth as the leech. I was thinking Tale of Two Cities, but the thing is, Sydney Carton comes clean. It has to be fictional literature, as in a novel, book, play (in writing), or poem. I'm thnking pretty hard and I've come up with a few things, and they could work but don't fit all criteria and might disrupt the paper in terms of flow.

Any suggestions are beyond appreciated.

Note: I know Macbeth would be perfect in this case, but I can't use any other Shakespeare.


Among things I've looked into and eliminated:

1984
Animal Farm
Steppenwolf
Brave New World
A few poems by Edgar Allan Poe

My teacher seemed to think there was a poem that would fit perfectly, but he could not think of it. I'd assume it would be a Greek poem or something of the sort.

Any help is beyond appreciated.

Grendel's Mother from Beowulf ?

Zeus posed in animal guise to have his way with mortal women. In one instance this led to the Trojan War--as William Butler Yeats hints at in Leda and the Swan.