Axel Becke was one of the most influential figures in the history of modern density functional theory (DFT). At a pivotal moment in the late 1980s and early 1990s, his remarkable physical intuition and deep understanding of electronic structure transformed the field and helped establish DFT as the dominant electronic structure method in chemistry. The impact of his work continues to be felt across chemistry, materials science, and condensed-matter physics.

In this memorial lecture, I will share personal reminiscences of Axel, reflecting on his unique scientific style, his generosity of spirit, and the profound influence he had on my own career and on generations of researchers. I will focus on two of his most important contributions: the B88 generalized gradient approximation for exchange and the introduction of hybrid functionals that combine density functional approximations with Hartree–Fock exchange. These innovations not only revolutionized practical electronic structure calculations but also shaped the direction of DFT research for decades. Even today, they remain central to the development of new functionals and to our understanding of the strengths and limitations of electronic structure theory. Through these examples, I hope to convey both the brilliance of Axel's scientific contributions and the enduring legacy he leaves to our community.