Researchers at Google applied GANs to crude sketches of imaginary creatures and managed to render them in rich detail. From their post on the Google AI Blog:

Today, we present Chimera Painter, a trained machine learning (ML) model that automatically creates a fully fleshed out rendering from a user-supplied creature outline. Employed as a demo application, Chimera Painter adds features and textures to a creature outline segmented with body part labels, such as “wings” or “claws”, when the user clicks the “transform” button. Below is an example using the demo with one of the preset creature outlines.

Unfortunately the demo seems to be broken at the moment so I wasn't able to experiment with it.