On April 20th, the Journal of Physical Chemistry published a Memorial Issue in honor of Klaus Schulten gathering more than 60 research articles. Klaus was an undisputed leader in theoretical and computational biophysics, recognized by his peers for his immense contribution to the field, and having devoted his entire career to establish the mechanisms that underlie cellular processes using the laws of physics. Originally planned to be a Festschrift to celebrate Klaus's achievements on his 70th birthday, the Memorial Issue initiative immediately triggered a unanimous positive response from friends, academic colleagues and longtime collaborators across the world. The many contributions assembled in the Memorial Issue of the Journal of Physical Chemistry lie at the confluence of theory and experiment, and cover a broad gamut of topics that were dear to Klaus, ranging from photosynthesis to molecular machines and membrane proteins. We gratefully acknowledge the many authors of the Memorial Issue, who enthusiastically accepted to pay one last homage to Klaus through contributions of very high scientific quality.