The Great Attractor is a gravitational anomaly observed as a large-scale bulk flow of galaxies toward a region roughly 150-250 million light-years away in the direction of the Centaurus-Norma supercluster. The existence and properties of this structure present challenges to Lambda-CDM because the inferred mass concentration required to produce the observed bulk flow exceeds what can be accounted for by visible matter and standard dark matter distributions in that region. The Great Attractor suggests either that mass is more concentrated than observed galaxy distributions would predict, or that the large-scale velocity field is not simply determined by local gravitational attraction but reflects deeper structural features of the universe. The basin of attraction is too large and too powerful for simple hierarchical structure formation models (Kashlinsky et al. 2010; Feldman et al. 2010).