The Teen Titans
cartoon version of Slade Wilson is pretty awesome. So naturally he's popular with the fancomics.
(Fanart from slinkers and jesskat83)
slinkers has a long series of cut-and-paste comics
on Robin's apprenticeship like this:
While jesskat83's stuff is a bit more, varied:
Yeah, xdoop's post reminded me of the last one. Can't imagine why.