15 U.S.C. §1127 (Extract)

The terms "applicant" and "registrant" embrace the legal representatives, predecessors, successors and assigns of such applicant or registrant.

37 C.F.R. §3.71(d) Trademarks.

The assignee of a trademark application or registration may prosecute a trademark application, submit documents to maintain a trademark registration, or file papers against a third party in reliance on the assignee's trademark application or registration, to the exclusion of the original applicant or previous assignee. The assignee must establish ownership in compliance with § 3.73(b).

An assignee, like an applicant, must be a natural or juristic person. See 15 U.S.C. §1127 and TMEP §803.