We bid farewell to the mathematician Peter D. Lax, who passed away on May 16, 2025. Lax received the Abel Prize in 2005 “for his groundbreaking contributions to the theory and application of partial differential equations and to the computation of their solutions.” The Abel citation further commented that “he has had a profound influence, not only by his research, but also by his writing, his lifelong commitment to education and his generosity to younger mathematicians.” We offer our sincere condolences to his family and friends.