The literature on co-creation platforms has been mainly focused on studying the crowds (i.e., participants) and that by investigating their motivations, their characteristics, and the strategies they use (i.e., cooperation, competition, coopetition). Therefore, researchers did not study opportunism even if its importance has been emphasized in prior research. To fill this gap, our research aims to explore and understand opportunistic behavior of actors or co-creators (i.e., brands, platforms, and participants) in the virtual context, especially that of co-creation platforms, using the method of Netnography in two famous co-creation platforms and a forum which is dedicated to different creators. Our research background, the main results as well as theoretical, methodological, and practical implications are presented in the related chapters.