M-dwarf (T_eff < 4000 K) planetary systems with at least one detected planet in the conservative sample of potentially habitable exo-planets (i.e., 0.5 R_⊕ < R_p < 1.6 R_⊕ or 0.1 M_⊕ < M sin i_p < 3 M_⊕) defined by the Habitable Exoplanet Catalog. The optimistic and conservative HZ regions for a one Earth-mass planet following the definition as set out by Kopparapu et al. (2013) are shaded with light and dark green, respectively. Only the planets in either the conservative or optimistic HZ of each planetary system are shown. White-filled and gray-filled points indicate nontransiting and transiting detections, respectively. The size of the circles is proportional to the planetary radius, estimated with the mass-radius relationship of Zeng et al. (2016) for nontransiting RV planets. The data used in this plot is further discussed in Appendix B. Plot inspired by Zechmeister et al. (2019) and Dreizler et al. (2020).