Kroloteans are small bipedal creatures with a scaly, sallow skin. They have lean faces with two horn-like extensions at the top, and pointy ears. Their eyes have three pupils.
They have a spoken language, Krollish, that, to human ears, sounds like random shrieks. Kroloteans can understand and speak English and Interlac, although they may be unable to vocalize the languages without aid.
The Kroloteans then arrived on Earth and kidnapped people, most notably UN Secretary-General Tseng Dangun. They used advanced robots to pose as their captives, in order to cover up their activities.
Queen Bee summoned a pair of Kroloteans to Bibbo's Diner, and handed over two captives to them for experimentation: Noor Harjavti, one of her political opponents, and Bibbo Bibbowski, who was a hapless eyewitness. The Kroloteans boarded lifelike robotic suits of the two, and took their place so they would not be missed.
The Krolotean who posed as Tseng was attacked by Lobo, who was both hired to track down his target, and put on a show for the locals. Wonder Girl and Batgirl tried to rescue the Secretary General, but eventually Lobo took hold of him and ripped the robot in half. He took the Krolotean with him.
The main Krolotean base was located under a New Orleans junkyard. Here, there were large numbers of Kroloteans, stolen technology, zeta platforms, and all their abductees.
When a security camera discovered the presence of the Team's gamma squad (Robin, Blue Beetle and Lagoon Boy), the Kroloteans swarmed the heroes. However, when their leader caught sight of Blue Beetle, he ordered a general retreat. The lead Krolotean then set the base to self-destruct, and escaped via Zeta-Beam along with the majority of the Kroloteans present. En route to free the abductees, Blue Beetle captured a Krolotean, who then led them to safety before the base exploded.
The Kroloteans managed to capture Miss Martian and Beast Boy, and content at having two "Meta-Earthlings", prepared to leave Rann. The Mechs with the prisoners did not reach the ship, as Superboy and Alanna intercepted it. While Superboy and Beast Boy damaged the ship, Miss Martian aggressively extracted information from the captured Krolotean general's mind, leaving him comatose. Two other stranded Kroloteans carried their drooling leader away, escaping into the jungles.
The Krolotean captured by Gamma Squad in Happy New Year was being interrogated (with little success) by Martian Manhunter, when Miss Martian forcibly extracted the Kroloteans' evacuation point from his mind. It was left a drooling vegetable.
The Manta-Flyer arrived at Black Manta's South Pacific base. Manta, revealed to be a villainous Aqualad, exited the submarine, flanked by the Kroloteans he evacuated. They were the last remaining unrescued Kroloteans.
South Pacific January 6, 20:32 HAST
While building a spaceship intended to return them home, the Kroloteans discussed the "Competitor", a rival they suspected to have employed the Main Man to reveal their existence to Earth. The Krolotean pursued by Blue Beetle and Bumblebee claimed to have been attacked by an agent of the Competitor.
When Kaldur discovered the base had been infiltrated by a joint Justice League and Team strike force, the Kroloteans aided the Manta Troopers with their war Mechs. Although the Mechs were handily destroyed, the Kroloteans pressed their attack when the strike force retreated. Superman tried in vain to persuade them to evacuate—there was an alien bomb set to blow. Unfortunately the Kroloteans did not trust him, and continued attacking the Man of Steel. All Kroloteans present were vaporized in the ensuing explosion.
Two Krolotean spectators were in attendance at the court trail of the Justice League. One Krolotean asked the other why the Justice League hadn't simply bribed the court to set them free. The second Krolotean told his fellow acquaintance that the League refused, to which the other scoffed that humans were savages.
In the comics, the Kroloteans are an alien race of gremlins from Sector 2812, who speak a language indistinguishable from modern German. They arrive on planets in groups, and mess with the native creature's DNA. A fairly recent creation, they have been retconned to be behind the transformations of long-time Green Lantern villains Hector Hammond and the Shark.
The Krolotean screams and shrieks are not vocalized by any voice actor: they were all sound effects by the Audio Circus Inc. post-production sound team.