How should we prioritize among all the species at risk of extinction? This course will grapple with the complex and consequential process of extinction from biological, geographical, and mathematical perspectives. Core themes will include the 1) nature(s) of extinction risks, 2) potential consequences of different kinds of extinction, and 3) considerations involved in setting priorities. Students will explore, handle, and analyze relevant data (e.g., evolutionary trees, species occurrence records, population censuses) to better understand extinction processes. With the aid of AI-generated hypothetical species, we will investigate hidden biases, debate the consequences of our choices, and explore possible prioritization strategies.