Monadic functors forgetful of (dis)inhibited actions

We prove a number of results of the following common flavor: for a category C of topological or uniform spaces with all manner of other properties of common interest (separation / completeness / compactness axioms), a group (or monoid) G equipped with various types of topological structure (topologies, uniformities) and the corresponding category C^G of appropriately compatible G-flows in C, the forgetful functor C^G C is monadic. In all cases of interest the domain category C^G is also cocomplete, so that results on adjunction lifts along monadic functors apply to provide equivariant completion and/or compactification functors. This recovers, unifies and generalizes a number of such results in the literature due to de Vries, Mart'yanov and others on existence of equivariant compactifications / completions and cocompleteness of flow categories.