Kelex is a Kryptonian robot as caretaker of Superman's Fortress of Solitude. He first appeared in The Man of Steel #1, in which he was one of Jor-El's robotic servants on the planet Krypton. Presumed destroyed along with Jor-El and the rest of Krypton, Kelex has nonetheless returned as Superman's primary robotic servant within the Fortress of Solitude.
Kelex has a streamlined design with a shiny, gold-orange finish. He has two long, slim arms which end in three pinchers, and possesses an anti-gravity module which allows him to hover. Connected to his body via a thick flexible cable, his head is flat, wide at the front and tapering to a rounded point at back. His obsidian faceplate is vaguely goggle-shaped, flat and featureless, except for an electronic waveform resembling an EKG which travels left to right across its surface.
When Kelex first appeared in 'The Man of Steel', he was only in one page of the first issue- he greeted his master, Jor-El, upon his return. Jor-El then ordered him to bring the baby Kal-El (who would become Superman) in his birthing matrix. It was revealed in conversation with another of Jor-El's servant robots that Kelex had served Jor-El for all of his life, much longer than the other robot had, and had never seen him like this. The robot didn't appear for the rest of the issue, nor for the rest of the miniseries. He was presumably destroyed along with the planet Krypton.
Later, when a Kryptonian device known as 'the Eradicator' was obtained by Superman, it tried to recreate Krypton on Earth, beginning with the North Pole. Superman stopped it, but the attempt had created the Fortress of Solitude. Along with the fortress had been created a group of robotic servants, one of which was a recreation of Kelex. Kelex was largely indistinguishable from the other Kryptonian robots who maintained the fortress.
The Fortress of Solitude was dramatically redesigned when Dominus took mental control of Superman, and was finally destroyed by Lex Luthor, severely damaging Kelex. When Superman returned to the fortress, he repaired the robot enough to enable him to speak. They were both sent to a ghostly replica of the Fortress, complete in every detail. Superman was able to keep a link to the ghostly fortress through Kelex, now reduced to a head, although Superman rebuilt Kelex's body when facing Brainiac 13 after realising that Brainiac was vulnerable to Kryptonian technology.
The fortress was later restored within a Tesseract (an infinite space within a finite containment), and Kelex was once again its caretaker. Natasha Irons reprogrammed Kelex so that he would speak more in slang, such as calling Superman 'Big Blue'. During the "Superman: Godfall" storyline, he even used 'yo mama!' as a comeback.
That incarnation of the Fortress was destroyed during the "For Tomorrow" storyline, and it was unknown whether Kelex survived its destruction. After Superman relocated his new portable fortress to South America, Kelex was seen again in the "Superman and Batman vs Alien and Predator" limited graphic novel series.