Picard-Vessiot theory is present in many settings like differential Galois theory, difference Galois theory, iterative differential Galois theory and several combinations of those. In this talk, we present a common framework for all these Picard-Vessiot theories by restricting to the categorical properties which all these theories share, and indicate how one obtains unifying proofs in this setting, e.g. theorems on existence and uniqueness of Picard-Vessiot rings, as well as on Galois groups corresponding to the Picard-Vessiot rings.