Well, first, lots of organizations don’t have “owners” per se. They might have boards and board chairs. Some don’t have any leadership at all. However, for those who do have a single individual as a ‘leader’ or financial controller (not always the same), Practitioner or PractitionerRole would be correct. Practitioner is anyone acting in their professional capacity. Whether you use PractitionerRole or not depends on whether you care “on behalf of what other organization” is the person acting as an ‘owner’ and/or what ‘hat’ do they wear when participating as an owner.
You’re not likely to find standard terminology in HL7-maintained code systems for something like this because it’s not something that most systems track or care about (or sometimes even applies).