Since the eBay descriptions don't mention it, the Transformers connection is (at least) two-fold:

1. Bill was responsible for the plots of issue 1 and 2 of the Marvel Transformers comic
2. He created Rocket Raccoon, whose comic was a backup strip in Transformers UK

He's needed full-time care since being the victim of a hit and run in 1992 that left him with severe brain damage.