What’s the story of the little green creature?
Pepe the frog!
Mainly a 4chan thing that has become associated with the Trump campaign.
https://en.wikipedia.org/wiki/Pepe_the_Frog
I assume you mean "Pepe the Frog"? I just found out about him a couple of days ago.
Apparently he was started back in 2004 on some website called "4chan", and he developed into a meme.
Around June, some pranksters started telling gullible media outlets that he was a symbol of "White National Racism". The media outlet bought it, and wrote a stupid article trying to convince everyone a cartoon frog named "Pepe" was now a symbol of White Nationalism.
But it's pretty much been confirmed that the people who told the media this were pretty much jerking their chain.
And now this meme has also trolled Hillary who foolishly repeated the claim.
The little green creature is the frog from 4chan, the online space Hillary claims is white supremacist.
They relish spoofing stuff.