This description is a bit… tentative, but I’ve been working on making a sort of world of my own where creatures and settings of my own doing inhabit and sort of do various things, inspired by the celestial, the infernal, and otherworldly. From beginning to ‘end’, it is not one too dissimilar to the existence we currently preside in.
These are arranged chronologically, and I hope the artworks below aim to paint a fitting picture for you, dear viewer.

Following their betrayal by consuming the accursed Apple of Knowledge, God banishes Adam and Eve from the Garden of Eden.
Eve, experiencing the effect of the Apple
The Devil was not the only creature facing corruption, as the Deity of Nature found itself slowly consumed by cancerous masses of fleshrot... but Nature always prevails, in the end.
The entrance to Hell is a perilous path beset with many challenges! Alternatively, you could just walk in through the horrible flesh monster's face hole.. that too.
A foolish follower leaves his pilgrimage and finds a wandering beast, not knowing he is before the object of his worship. He opens his mouth for the last time before he realizes.

A changed denizen of Hell contemplates their new existence as a collective mass of consciousness and faces.

The Devil lounges in the deepest recesses of Hell, surveying his turned spawns; he realizes he cannot wait any longer.
One of the many accursed denizens of Hell.
One of the many accursed denizens of Hell.
One of the Many accursed denizens of Hell.

There are only two ways to enter Hell, to die or to be summoned there, but for those lacking passage, there is a third. If you seek the Guide he may graft the Mask of the Fallen on your face, granting entry, but once it peels off, you'll never be the same.
A shapeshifted demon corrupts a horrid monster further into its grasp
One of the many accursed denizens of Hell.
The Void King of Hell
Portrait of Lord Ghrushmere, Mad Lord of Hell. He could barely sit still long enough for the Court Painter to capture this visage.
An archdemon of hell, opening its cruel weakness

God realized that no creature could ever match his being and thus he dispersed his living essence across the cosmos, his remains turning into the stardust that would become... everything.
Several millenia after the Great Battle, the remains of the Devil are little more than sunbleached adornments on the natural landscape.
Ah, the age old clash between nature and technology, the old and the new, the eternal and the ever-changing. It will never end.

On another system in the future, a lone cyber-enhanced redneck has been sitting on a pier for 5 hours, catching himself a big'un, a certifiable eldtritch sea monster to mount on his living room wall. A good Tuesday for him.
When cybernetic enhancements became commonplace, there were some humans who don't know where the line between comfort and insanity lies, constantly pushing the boundaries before something gives.
Wandering doctor and adventurer Dr. Gilberto's Recovered Findings #38, on the union of machine and man.

A sleep-monster divulges its ugly form before capturing their next unseeing victim.

The Giver is a monster who materializes out of the blood, guts, and viscera of a battlefield and drains the remains of the fallen, sprouting fruits and flowers that induce the happiest memories of the dead if consumed. It dissipates once the last remains are converted, leaving behind only its broken mask.