This chapter explores the ethical challenges of artificial intelligence (AI) across various stages of its lifecycle, from data collection to deployment. Key issues such as bias, accountability, privacy and surveillance, and emerging ethical dilemmas are critically evaluated in this chapter. Through case studies and real-world examples, the chapter highlights how AI systems have perpetuated discriminatory practices, compromised individual privacy, and presented difficulties in assigning responsibility for decisions. It also outlines mitigation frameworks, such as fairness-aware algorithms, explainable AI, privacy-preserving technologies, and ethical oversight mechanisms, to address these challenges. The chapter emphasizes the need for proactive governance, transparency, and collaboration among stakeholders to ensure that AI systems are developed and deployed responsibly. This chapter provides a strong foundation for understanding the ethical challenges of AI and sets the stage for the next chapter, which will explore case studies in AI ethics, offering practical insights into how these challenges manifest in real-world applications.