Final answer:
A course developer with proprietary interest in a course, who may deliver and market it, is known as a course proprietor or a course owner.
Step-by-step explanation:
A course developer who has a proprietary interest in the course and may deliver the course and/or market it is typically known as a course proprietor or a course owner. This individual not only creates the course content but also holds the rights to it, which allows them to have exclusive control over delivery and marketing. Such a role is crucial in the context of online education and professional training programs, where the uniqueness and control of content can be significant competitive advantages.