Since the inception of graph C*-algebras, groupoids have been an important tool for studying them. In this talk, I will first briefly cover the basics of groupoids, their C*-algebras, and Steinberg algebras. Then, I will show how to construct a groupoid from a graph so that its C*-algebra is isomorphic to the corresponding graph C*-algebra, and its Steinberg algebra is isomorphic to its Leavitt path algebra. Finally, I will explain how to use the functoriality of groupoid C*-algebras (via groupoid actors as morphisms) to study the functoriality of graph algebras using Cuntz–Krieger dynamical families. (Joint work with Ralf Meyer.)