This master’s thesis explores product ownership within the context of software development projects, primarily focusing on identifying key personality traits essential for effective product ownership. The research question is: "What are the key personality traits associated with effective product ownership depending on the type of software development project?". Critical insights were discovered through comprehensive literature research regarding the fundamental traits that distinguish an effective product owner. This research analyzes existing personality traits and their relevance to product ownership. In addition to the widely recognized Big Five personality traits, the research identified the significance of emotional intelligence, openness to experience, conscientiousness, agreeableness, and self-efficacy, providing a holistic perspective of the multifaceted product owner role. A distinctive facet of this thesis lies in its ability to contextualize the personality traits of various software development project types. Five specific project types - custom software development, product development, legacy system modernization, maintenance, and integration projects - were identified, and the thesis explains how these projects demand distinct combinations of personality traits for success. Furthermore, this research provides the practical tool (artifact), the "Product Owner: Key Personality Traits Guideline", and it is designed to empower hiring managers, team leads, and department heads with a structured framework for evaluating the personality traits of product owner candidates and matching them with the unique requirements of their projects. This thesis contributes to the literature and practical application in the software development industry. By offering an improved understanding of the product-owner role and its various demands, this thesis provides a strategic approach to hiring and project placement, ultimately enhancing the likelihood of project success. While it achieves significant milestones, it also identifies potential for future research, including a quantitative exploration to solidify qualitative findings further. This thesis contributes towards more effective product ownership and tries to influence practices within software development.