After the Beyonder and the Molecule Man learned that their power derived from the dimension of an unrelated race of beings known as the Beyonders, which is responsible for the power of the Cosmic Cubes, they merged themselves together into a new Cube. Like all Cosmic Cubes, it eventually developed into a sentient being, after which it sent the Molecule Man's self back to Earth. This sentient being, which retained the Beyonder's essence and powers, took on a new female form, and called itself Kosmos.
Kosmos was created by Len Kaminski and Greg Capullo and first appeared in Fantastic Four Annual #23.
Much like the character that spawned it, Kosmos' nature and existence have been the subject to inconsistent takes by different writers. Kosmos has been shown as being nothing but an evolved form of the Beyonder and at other times a separate being entirely. Kosmos first appeared in a new mortal form, as Maker, in Thanos #8. The Maker form was killed off-panel in Silver Surfer #3, but what this truly means for the Beyonder, and perhaps even Kosmos, has never been explored.
Major Story Arcs
Beyond and Back
Kubik, another evolved Cosmic Cube being, began tutoring Kosmos, who had forgotten much of what it learned in its previous form. Exploring the existence of the Universe and its many Cosmic entities, Kubik and Kosmos became close. They continued to tour the multiverse together until a frustrated Molecule Man forced the Beyonder to take his original form again. After Molecule Man defeated the Beyonder, Kubik showed up asking him to stop. The Molecule Man realized that Kubik was falling in love with the Kosmos form and restored the Beyonder and Kosmos to her former state.
Kosmos created a new mortal form for herself, the Maker. This mortal form proved to be too much for her mind to bear, and she destroyed an entire Shi'ar settlement. After being captured by the Imperial Guard, Oracle shut down her mind and she was sentenced to the pan-galactic prison Kyln. Gladiator learned from Oracle that the Maker was evolved from the Beyonder and he volunteered to be placed in the Kyln to keep an eye on it and destroy it if necessary.
After a riot at the Kyln set her free, the Maker gathered a following of inmates who began worshipping her. Gladiator and Star-Lord, among others, opposed the Maker and even gained the help of Thanos, who was visiting the Kyln on a pilgrimage. Thanos, also aware of Maker's origins as the Beyonder, telepathically shut her mind down to contain her true power and potential omnipotence. Her insane mind thus became imprisoned in her own body.
The Kyln prisons were destroyed during Annihilation and the Maker was killed in the battle. Thanos sent the Fallen One to the remains of Kyln to investigate her fate and potentially recruit her as an ally. The Fallen One only found Kosmos' lifeless mortal form, dead, but what this means for the Beyonder's power, contained within, was unseen.
Powers and Abilities
Kosmos, evolved from the Beyonder, can use all of the Beyonder's powers but opted to not use them much. Kosmos was reserved in the use of her power and her true extent and limits were not displayed. Generally speaking, however, she can be assumed to possess all the standard powers of a sentient Cosmic Cube, such as those wielded by Kubik or the Shaper of Worlds. However, in her Maker form, her powers were limited due to her new mortal body.