Learn English – What do we call a person who does branding

That party is quite often referred to as the contractee

Project owner (also called client or principal) or other entity that enters into a contract with a contractor or vendor and receives specified goods and/or services under the terms of the contract (such as a purchase order).

The verbiage, "hereinafter referred to as the 'Contractee'” is often found in legal docments.
Here's an example document using that terminology.

I decided to turn to existing forms rather than just reaching into the air for an obscure term. Here's the USCIS I-129F form, which is a government form that might be prepared by someone other than the petitioner. They call this person the preparer.