They're truly a rarity, but that's easily obvious because most anime is more watchable than Western fare to a majority of animation ethusiasts. Sad, but true.
And this is (unfortunately) coming from someone who Despises 98% of what Japan puts out...But not without good (IMHO) reasons...
However, to stay on subject, I can't remember for the daeth of me the last time I've seen someone cosplaying Western fare unless it's for Adventure Time (I've come by some cosplays of it on Deviant Art of all places).
This is where I, the Vampire Mistress, proudly reside: http://liberal.nationstates.net/nation=nova_nacio
TBH, No, it doesn't. Just as long as people recognize said character you're disguised as is all that counts.
Though it does help one's case a little to dress as (but I don't completely approve of it) something nostalgic.
edited 8th Nov '11 1:48:53 PM by LostAnarchist
This is where I, the Vampire Mistress, proudly reside: http://liberal.nationstates.net/nation=nova_nacioI remember having seen Joker and Harley Quinn cosplayers on the con I was a few weeks ago. There were also some cosplayers of other cartoons, but I can't quite remember them or didn't recognize from what they were.
There is another thing, besides clothing, though. The art style and the variance in facial features that comes with it. Some use... some stuff (not sure what exactly, maybe wax) to "change" their facial features or, less elaborately, wear mask to resemble the characters more.
edited 9th Nov '11 5:25:07 AM by Nyarly
People aren't as awful as the internet makes them out to be.I don't have much experience with cosplay at all, but there's one girl on Deviant ART who has some cosplay pics of herself as Izzy from Total Drama Island that are pretty good... compared to most of the TDI cosplay I've seen, anyway.
There's RabbitInTheMoon, who's costumes of Bridget from An American Tail border on Uncanny Valley.
http://www.cosplay.com/photo/1131973/
Relevant.
Not really a fan of the music, but it's really well done. Also, check out this channel: https://www.youtube.com/user/MangoSirene?blend=5&ob=5
edited 25th Nov '11 12:28:18 PM by StarOutlaw

Because Cosplays of Western Cartoons need more love.
What were your most favorite ones?
Yep, I'm still here.