- "You cannot stop us. We are many." — Starro
Starro is a race of intergalactic parasitic starfish that fly across the universe to conquer various civilisations through replicating itself into smaller drones, latching onto the face of a host and controlling their minds and central nervous system.
Their ability to dominate the minds of entire populaces with ease makes them an incredibly dangerous threat, and one of the earliest and greatest enemies of the Justice League of America.
The first recorded encounter of a Starro on Earth saw the creature empower three starfish and wreak havoc in Happy Harbor by exploding an atom bomb and absorbing its energy, kidnapping scientists and absorbing their brain power and placing the residents of Happy Harbor and Rhode Island under mental control.
Eventually these starfish were stopped by Aquaman, Flash (Barry Allen), Green Lantern (Hal Jordan), Martian Manhunter, and Wonder Woman when they found that Happy Harbor resident Lucas "Snapper" Carr was not enslaved due to the lime solution that was spread on his lawn. While the Starro was defeated when the heroes coated it with quicklime, a segment of it survived and regenerated into a full Starro, but was stopped by Aquaman before it was able to renew its planned conquest.
Another Starro eventually appeared, initially a small drone, the Starro forced humans to nurture it until it could assume larger proportions. Creating millions of miniature "spores", the Starro took control of the entire population of New York and managed to also take control of several members of the Justice League until it was defeated by the extreme cold of the city's winter.
In another incident, when Superman investigated a strange phenomenon causing the citizens of Metropolis to begin acting like apes, he is accidentally transported to an alternate universe Earth called "Earth-C". Meeting Captain Carrot and his Amazing Zoo Crew, Superman aids the animal heroes in defeating their own version of Starro and then takes the defeated Starro back to his universe.
While imprisoned, the Starro later manages to convince Justice League Europe that it was dying and wished to return to space. Aided by Kilowog, the Starro returns to the ship that the first Starro used to get to Earth and betrays the Justice League by causing the vessel to explode and release thousands of smaller "spore" Starros over Western Europe. The Starro is finally defeated when Ice (Tora Olafsdotter) uses her ice powers to freeze it; causing the smaller "spores" to become inert.
Another Starro and its "spores" takes control of the Flash (Wally West) and the population of Blue Valley. Although the JLA intend to intervene, they are advised against doing so by the Spectre (Hal Jordan), who reveals the Starro's intention is to lure and capture the heroes and use them to form an army to conquer the galaxy. To avoid this the JLA requests that the Spectre temporarily remove their powers and eliminate the potential threat they may pose if assimilated. While powerless, the heroes distract the Starro long enough for Batman to disable it with extreme cold.
It is later revealed that this Starro was a scout for a larger Starro that soon arrived and covered Europe with its body; enslaving the human race while they sleep. Dream of the Endless aids the JLA in defeating this Starro.
While during the Infinite Crisis incident, a Starro appears as a member of Alexander Luthor, Jr.'s Secret Society of Super Villains, it can be assumed that more Starros await in the cosmos beyond the galaxy all capable of assimilating entire planetoid civilizations into their collective.
- Starro appear in various locations as well as in the Central City Starro Deluge Zone during the Starro the Conqueror event.
- Starro appear in various locations as well as in the Central City Starro Deluge Zone in the Deluge episode.
- Starro first appeared in Brave and the Bold #28 (February–March 1960).
- A Starro can asexually generate parasitic clones from its own body and command them to act in accordance with its will. By extension, a Starro can also transform ordinary Earth-based starfish into loyal Starro agents.
- Members of the Starro species come in numerous sizes; ranging from the size of a human hand to the size of a planetary ocean. While the smaller members possess the ability to control the minds of their hosts, the larger breeds can radically alter the climate, topography and geography of a planet for terraforming purposes.