Ring dark and anti-dark solitons in nonlocal media are found. These structures have, respectively, the form of annular dips or humps on top of a stable continuous-wave background, and exist in a weak or strong nonlocality regime, defined by the sign of a characteristic parameter. It is demonstrated analytically that these solitons satisfy an effective cylindrical Kadomtsev-Petviashvilli (aka Johnson's) equation and, as such, can be written explicitly in closed form. Numerical simulations show that they propagate undistorted and undergo quasi-elastic collisions, attesting to their stability properties.In nonlinear optics, spatial dark solitons are known to be intensity dips, with a phase-jump across the intensity minimum, on top of a continuous-wave (cw) background beam. These structures may exist in bulk media and waveguides, due to the balance between diffraction and defocusing nonlinearity, and have been proposed for potential applications in photonics as adjustable waveguides for weak signals [1].In the two-dimensional (2D) geometry, spatial dark solitons, in the form of stripes, are prone to the transverse modulation instability (MI) [2], which leads to their bending and their eventual decay into vortices [3]. However, the instability band of the dark soliton stripes, may be suppressed if the stripe is bent so as to form a ring of particular length. This idea led to the introduction of ring dark solitons (RDSs) [4], whose properties have been studied both in theory [5,6] and in experiments [7], and potential applications of RDS to parallel guiding of signal beams were proposed [8]. RDSs have also been predicted to occur in other physically relevant contexts, such as atomic Bose-Einstein condensates [9] and polariton superfluids [10,11].While the above results rely on the study of nonlinear Schrödinger (NLS) models with a local nonlinearity, there exist many physical settings where the use of NLS models with a nonlocal nonlinearity are more appropriate. This occurs, e.g., in media featuring strong thermal nonlinearity [12] or in nematic liquid crystals [13], where the nonlinear contribution to the refractive index depends on the intensity distribution in the transverse plane. It has been shown that dark solitons in one-dimensional (1D) settings exist in media with a defocusing nonlocal nonlinearity [14][15][16][17][18][19] while, in the case of stripes, transverse MI may be suppressed due to the nonlocality [20]. The smoothing effect of the nonlocal response was shown to occur even in the case of shock wave formation [20][21][22][23], or give rise to stable 2D solitons [24]. Here we should note that, generally, pertinent nonlocal models do not possess soliton solutions in explicit form (other than the weakly nonlinear limit [25]). As such, various techniques have been used to analyze soliton dynamics and interactions, with the most common one being the variational approximation, where a particular form of the solution is chosen [13,[26][27][28][29]. However, to the best of our knowledge, RDSs in nonlocal medi...