User blog comment:PanickingPines/Bill's Physical Form?/@comment-26863672-20151021210827

I don't think he'll necessarily take a human form. Somehow Bill as a human seems to undermine his power. They're more for his pawns/personal gain. But whatever his true form is, it's going to be BIG (such as the 6-armed tri-part form).

Also, for the record, the "meat" version of him is muscle tissue.