Comparison of our modeled T_eff with the average T_eff of literature studies on RSGs based on the line-free continuum method (red triangles), SED method (green inverted triangles), J-band spectral lines (yellow circles), TiO bands (magenta squares), and i-band spectral lines (cyan stars) in a range of metallicities. TiO results from this work are marked with a thick border; larger squares represent larger sample sizes. The solid black line represents the mean T_eff of a population of RSGs computed with the POSYDON population synthesis code (see Sec. 3.3). The gray shades indicate the standard deviation from the mean T_eff of the RSG population at each metallicity. NGC 300* includes NGC 300, NGC 247, and NGC 7793; NGC 55* includes NGC 55 and NGC 1313.