The Goddess was a cosmic-entity from Marvel Comics created by Adam Warlock after he separated his "good" and "evil" halves during his brief possession of the Infinity Gauntlet - the "evil" half became the insane Magus while the "good" half became the female Goddess, she represented Warlock's deeply suppressed feminine side and originally seemed benign but was revealed to be much more antagonistic than she first appeared: gathering hundreds of heroes and villains to her side she began a universe-wide crusade that elevated her into a divine state in which she was worshipped as a supreme being, during this time she had Moondragon utilise her formidable psychic abilities to brutally attack anyone that dared question her rule - going as far as putting Professor Charles Xavier into a coma for trying to communicate with her, Spider-Man also fell victim to Moondragon's assault and Thor was also attacked but eventually resisted and broke away from the Goddess' cult.
In order to amplify her powers The Goddess gathered many Cosmic Containment Units and created a Cosmic Egg once she had 30 of these artefacts, with this Cosmic Egg she gained the powers of a true deity and began to grow ever more tyrannical in her methods - it was during a trip into The Goddess' mind that Adam Warlock was informed of her true plan for reality: she planned on eliminating all of reality in order to destroy evil, making her a cataclysmic threat to every living being (although Eternity and Infinity didn't see her as a threat).
After this The Goddess' plans were revealed to the universe when an illusion showed her destroying all the stars in the universe, as her followers began to abandon her she lost her unlimited power and fought against Warlock in an astral-state, believing herself to be a supreme being - and for a while she overpowered him.. however Thanos and a revived Professor Xavier joined the battle and evened the playing field - nearing defeat The Goddess tried to flee back to the Cosmic Egg to kill Thanos and Professor Xavier but was dismayed when Adam Warlock managed to gain control of the device instead and used it against her, she was then imprisoned inside the Soul Gem by Thanos - who proceeded to use the Cosmic Egg to put right everything The Goddess had done (this may seem strange at first but Thanos has shown himself to have a twisted sense of honor - despite his genocidal nature).
While trapped inside the Soul Gem the Goddess found herself unable to communicate with anyone save for Magus and even then the two were like ghosts, unable to even touch one another as she learnt when she tried to attack him - and there she seemingly remains.. trapped forever in limbo.