We investigate the algebra generated by the topological Wilson loop operators in WZW models. Wilson loops describe the nontrivial xed points of the boundary renormalization group ows triggered by Kondo perturbations. Their enveloping algebra therefore encodes all the xed points which can be reached by sequences of Kondo ows. This algebra is easily described in the case of SU(2), but displays a very rich structure for higher rank groups. In the latter case, its action on known D-branes creates a profusion of new and generically non-rational D-branes. We describe their symmetries and the geometry of their worldvolumes. We brie y explain how to extend these results to coset models.