Background The evaluation of attractiveness varies from one civilization, culture, and environment to another and between individuals. Gender can also play a role in determining the standards of attractiveness. The purpose of this study was to evaluate the effect of the rater's gender on the assessment of adult facial attractiveness with a vertical and horizontal growth pattern in patients with skeletal Class I malocclusion. Methodology The study sample comprised extraoral photos taken before the treatment of 120 patients (30 males and 30 females in each group) with skeletal Class I malocclusion and vertical and horizontal growth patterns according to the Bjork sum aged between 18 and 25 years. A panel of 30 laypersons (aged 19-25 years with an average age of 23 ± 0.53 years), including raters from both genders, were selected equally using a disproportionate stratified sampling method through a computer-generated list. The raters used the visual analog scale (VAS) to provide a score for each photograph's aesthetic quality. The most attractive group, which received the greatest aesthetic score, and the least attractive group, which received the lowest aesthetic score, were the two groups formed based on each photograph's mean aesthetic scores. Overall, 13 patients were chosen for each group. Subsequently, the average assessment score for every patient photo set was determined. Independent-sample t-tests were employed to ascertain if the raters' gender made a statistically significant difference in assessing patients with vertical and horizontal growth patterns. Results There were statistically significant differences between the gender of raters in evaluating female patients with vertical growth patterns (p < 0.001), where the average rating of the female raters was significantly greater than that of the male raters in evaluating female patients. In addition, there were statistically significant differences between the gender of raters in evaluating female patients with horizontal growth patterns (p = 0.009), where the average rating of the male raters was significantly greater than that of the female raters in evaluating female patients. Conclusions There is a limited effect of the rater's gender in evaluating facial aesthetics. However, the facial features of female patients with long faces are preferred by females more than males, and males are more critical in evaluating these patients. On the other hand, males favor the facial features of female patients with short faces more than females, and females are more critical in evaluating these patients. These results suggest considering patients' personal characteristics with vertical and horizontal growth patterns during diagnosis and treatment planning.