The past few years have seen an explosion in the discoveries of Pluto- and near Pluto-sized bodies in the outer solar system, giving rise to a new classification of “dwarf planets.” Like Pluto, each of these largest dwarf planets has a unique story to tell about the history and evolution of the solar system. I’ll discuss the discoveries of these objects and the new views of giant collisions, stellar encounters, and planetary rearrangement that we are gaining from their study.