This paper explores how minoritized Computer Science (CS) students articulate their sense of critical agency to positively impact the world around them, both for today and the future, when participating in a Girls Who Code program focused on ethics, equity, and underrepresentation in computing. Observations, interviews, and surveys were conducted across five sites in which students read a graphic novel (entitled "Power On!") about inequities in technology and CS education and experienced activities about computing for social good. Students described their agency through "educator," "advocate," and "creator" roles with computing, and described key curricular and pedagogical factors supporting their critical agency in CS for All. Implications for CS curricula, professional development, and policy efforts geared toward increasing equitable access and engagement with CS are discussed.