Let's start with a brief definition of the term "creditor."
For purposes of our discussion here, the term "creditor" means a person who regularly extends credit that is subject to a finance charge or payable by a written agreement in more than four installments (not counting a downpayment) and to whom the obligation is initially payable, either on the face of the note or contract, or by agreement when no note or contract exists.
In general, TILA imposes liability only on creditors for violations of its provisions.
Some exceptions include the requirement that servicers provide notices of transfer or assignment of mortgage loans, certain obligations of loan originators, and liability of assignees for violations apparent on the face of a disclosure statement, except when the assignment was involuntary.
So, typically, a borrower who sues a defendant for violating TILA must tie the violation to the creditor (or, in the exceptions just mentioned, the servicer, loan originator, or assignee).