The Vanguard are a mobile team of super powered beings who see their territory as the entire cosmos. Roaming through space in their sentient spaceship, Drone; they visit planets doing what good they can before leaving for the next solar system. Their membership is made up of individuals who command some fundamental cosmic power, such as White Dwarf, Solaar, and Anti-Matterman.
The Vanguard's one and only visit to earth thus far was largely a case of mistaken identity. In an attempt to capture Superman, the Vanguard succeeded only in netting one of his robotic duplicates. The Teen Titans arrived on the scene and the two teams discovered that Brainiac had murdered Vanguard member Black Nebula and abducted Superman to serve as an organic power source for his interstellar war machines.
Only the combined strength of the Vanguard and the Titans could defeat Brainiac and return Superman to Earth. Although grateful to the Titans for their help, the Vanguard chose to resume wandering across the light years of space rather than remain tied to a single planet.