Sometimes the best decision may be to not design. But you can “not design” in different ways. There are emerging discussions of using design's destructive potential to hinder, eliminate, “undesign” unwanted technologies and practices. In this paper we argue that informed and carefully crafted not-doings should also be considered valid and generative design acts. Through discussing a series of inaction-related design projects we propose the concept of design (in)actions. An (in)action is the informed, articulated and designerly decision to not act. Through the concept of “designer killjoy” we frame risks and stakes of such moves. We discuss how design inactivism – design (in)actions mobilised for activist ends – inform and develop current conceptualisations of design activism. Finally, we propose design (in)actions as a useful tactic for “gracious design”: more-than-human design moves characterised by forsaking human privilege through leaving be.