|Type||Weapon of mass destruction|
A Sun-Eater is a living nebula with the ability to drain whole stars of all their energy; this snuffs out the star and causes its solar system to freeze (and all living beings in it to die). The Sun-Eaters were created by the alien race known as Controllers as a way to destroy entire worlds that they judged to be too "evil." Each Sun-Eater was kept in a dormant state until needed, watched over by a Controller.
A creature called a Sun-Eater was first depicted in the Legion story in Adventure Comics #305 (February, 1963), and was a fiery green humanoid that "roams through space, feeding on solar bodies, absorbing their heat and energy. In a brief vignette, the creature is driven off by Mon-El's heat vision.
Another being called the Sun-Eater was first seen in Adventure Comics #352 (Jan. 1967), in a story that took place in the 30th century, the setting of the Legion of Super-Heroes, by writer Jim Shooter. Its keeper had gone insane and had released it on the Milky Way galaxy unprovoked. To stop the star-sized creature, the Legion actually recruited some of the worst criminals in the Galaxy to help them (these criminals would stay together to form the Fatal Five afterwards.) But in the end, only one way to stop it was found: an "Anti-Energy" bomb would have to be detonated inside its core. Only Superboy was invulnerable enough to deliver the bomb inside, but he was weakened by radiation inside the Sun-Eater (from the red suns it had already consumed). Ferro Lad, a new addition to the Legion who possessed the power to turn into living iron, could resist going inside the Sun-Eater, but not the bomb's explosion. Heroically, he stole the bomb and delivered it anyway, killing himself and destroying the Sun-Eater, thereby saving the galaxy.
During a period when Superman was sent bouncing back and forth through time following a confrontation between Booster Gold and a renegade member of the Linear Men, he aided the Legion in confronting another Sun-Eater of the type seen in the 1967 story. Although Legion member Wildfire tried to plant another bomb in the heart of the Sun-Eater, the plan failed when he was detected and the Sun-Eater's internal defenses forced him to retreat. While Superman and the other Legion members occupied the Sun-Eater's attention, Wildfire traveled to the heart of the Sun-Eater and abandoned his containment suit- he was naturally a being of pure energy-, leaving Shrinking Violet to reconfigure his suit's internal workings to turn it into a weapon. The Sun-Eater was subsequently destroyed, with Superman throwing Violet to safety at the last minute, although the resulting explosion sent him hurtling through time once again.
Another Sun-Eater appeared in DC Comics Presents #43, in a story set in the 20th century. The space villain Mongul killed a Controller and unleashed his Sun-Eater to destroy Earth in revenge for his defeats at the hands of Superman. The Legion travelled through time to the present to help Superman save the world. While Superman fought Mongul, Wildfire apparently sacrificed himself by exploding his anti-energy body inside the Sun-Eater's core, but he managed to re-form.
After the Zero Hour event, history was changed so that the events chronicled in earlier stories had never occurred. In the new Legion continuity, the Sun-Eater was a myth, invented by the President of the United Planets to unite the member worlds against an external threat, thereby increasing her power base. This plan was exposed by the Legion. During this storyline, it was mentioned in passing that Sun-Eaters had last been seen in the late 20th century.
This led into the Sun-Eater's first post-Zero Hour appearance, in the Final Night miniseries (1997) (set in the present day, rather than the Legion's future). A rogue Sun-Eater destroyed several planets, eventually reaching our Solar System and snuffing out the Sun. The heroes of Earth were powerless to stop it, until Parallax sacrificed his powers and life to destroy it and reignite the Sun.
In 2005's The Return of Donna Troy miniseries, it was discovered that a planet called Minosyss hosted a Sun-Eater factory hidden deep inside. One of its Sun-Eaters was used to kill Hyperion and Thia, two of the Titans of Myth.
In the non-continuity title All-Star Superman, a baby Sun Eater was part of the intergalactic zoo in Superman's Fortress of Solitude. It was fed on miniature suns, created by Superman with a cosmic anvil from New Olympus. The infant creature was eventually released into the wild by Superman, but came to his aid when he was fighting Solaris only to be killed by the evil star.
In the series 52, Lobo, Starfire, Adam Strange, and a member of the Green Lantern Corps named Ekron defeated Lady Styx by pushing her into a group of Sun-Eaters. Animal Man was later able to tap the powers of the Sun Eaters, acquiring "migration maps", the ability to survive in space, and other traits.
Other media 
In the two part Legion of Super-Heroes animated episode "Sundown", a Sun Eater is released from a weapon holdings platform by a renegade Controller. It is a living metal sphere capable of generating a massive energy cloud that can drain stars of their energy. Brainiac 5 explains the Sun Eaters were created during an interstellar war called the "Great Crisis". Created to scare the two sides into ending the conflict, the weapon was only used twice, but then proved impossible to destroy or dismantle. The Legion teams with the Fatal Five to create a weapon that can destroy it. When the weapon fails to detonate due to a faulty connection, Ferro Lad sacrifices himself to act as a conductor.
In the All-Star Superman film, the Sun-Eater fulfills the same function as it does in the comic.
See also 
- Adventure Comics #305 (February, 1963)
- Adventure Comics #353 (February 1967)
- Infinite Crisis #7 (June 2006)
- Justice League of America (Vol. 2) #34 (August 2009)