  We numerically construct asymptotically anti-de Sitter (AdS) black holes in
four dimensions that contain only a single Killing vector field. These
solutions, which we coin black resonators, link the superradiant instability of
Kerr-AdS to the nonlinear weakly turbulent instability of AdS by connecting the
onset of the superradiance instability to smooth, horizonless geometries called
geons. Furthermore, they demonstrate non-uniqueness of Kerr-AdS by sharing
asymptotic charges. Where black resonators coexist with Kerr-AdS, we find that
the black resonators have higher entropy. Nevertheless, we show that black
resonators are unstable and comment on the implications for the endpoint of the
superradiant instability.
