Owner
In short
Broader than the title holder. The statute reaches an agent and anyone with authority to perform or authorize the work, with a tenant and a property manager named expressly.
In full
A contractor's intuition is that the owner is whoever holds the deed. The statute is wider than that, and the width is what makes the MRRA exclusion work.
A.R.S. § 42-5075(S)(8) defines owner as the person that holds title to the real property or improvements that are the subject of the work, as well as an agent of the title holder, and any person with the authority to perform or authorize work on the property or improvements, including a tenant and a property manager.
Why it matters. The MRRA exclusion at § 42-5075(P) applies to a contract with the owner of real property. If owner meant the title holder alone, a tenant's remodel contract and a property manager's repair order would be outside the exclusion and taxable under prime contracting. They are not, because both are owners for this purpose.
A second rule operates inside the same definition, for the MRRA exclusion only. A person hired by a general contractor that was hired by an owner, or a subcontractor of that general contractor, is considered to be hired by the owner. A subcontractor two levels down the chain performing maintenance, repair, replacement or alteration therefore keeps the exclusion.
Owner status does not by itself make a person a prime contractor. A person who owns real property, engages one or more contractors to modify it, and does not modify it themselves is not a prime contractor, regardless of any contract for sale or subsequent sale of the property — subject to two exceptions at § 42-5075(E) and (R). Where an owner improves property for sale, the city Speculative Builder and Owner-Builder classifications are the ones to check.
A.R.S. § 42-5075(S)(8), (P), (S)(10), (E), (R)