The present study aims to estimate the prevalence of bullying in Greek elementary schools and to study the risk factors that lead to bullying episodes. A structured questionnaire was given to 221 teachers of elementary schools and 71 kindergarten teachers from urban and rural Greek schools. They were asked to note the forms and the frequency of aggressive behaviors that they had witnessed during the school years 2020–2021 and 2021–2022, as well as the sociodemographic characteristics of the aggressive children involved. Statistical analyses of the data were conducted, and the obtained results show that specific forms of aggression are significantly correlated with gender and low academic performance. In addition, there is no form of aggressive behavior that is associated with the perpetrator’s age, nationality or family status. Further, the results of the factor analysis revealed four dominant factors in the aggressive behavior observed by teachers. The forms of bullying and the prevailing factors of aggressive behavior that dominate in Greek school settings are reported in the present study. Furthermore, a novel evaluation tool for teachers could potentially be developed based on the results of the present study.