AI has entered and is transforming a wide range of domains, from product development to entertainment, from scientific research and healthcare to autonomous weapons and lethal AI. It has been called the fourth industrial revolution and is being rapidly adopted across industries, government systems, and daily life by citizens and consumers in a global and pervasive transformation, raising fundamental questions around our collective future. Progress has been truly outstanding, and one might argue that we are witnessing an AI revolution powered by a collection of already mature computational techniques and the cumulative effect of a large amount of high-quality data on decision algorithms. Research on the ethical aspects of AI is as old as the field itself, yet now, as AI permeates our societies in increasingly profound ways, the same ethical questions exist with an expanded scope and new urgency. These questions concern not only the benefits and risks of specific systems but also the institutions and processes involved in the development and use of AI. Many of these questions concern fundamental values. What do we count as data privacy worth protecting and why? Under what conditions is it acceptable for AI systems to make decisions that infringe on human autonomy? What is the relationship between fairness and equality, and how should these values be reflected in decision algorithms? How should the power of AI systems be distributed, and what roles should be entrusted to citizens, their representatives, or other stakeholders such as private actors? What types of transparency, independent oversight, due diligence, and recourse are needed, under what conditions, and why? Furthermore, how will data be used for training and evaluation? What safeguards can be put in place to avoid manipulation, disinformation, and discrimination? These are high-stakes questions that demand responsible solutions for a variety of technological challenges, tailored to different needs and issues, and that require more than philosophical inquiry, as a significant body of research has started to emerge in science and technology studies, political theory, ethics, machine learning, and other computational subfields.