Reverend Theo: Wow, you really do think you've become a god.
Petey: I'm just trying to do what I think a god would do if he were in my position.
Damien, Big Bad of El Goonish Shive'sPainted Black arc, created in a lab but believing himself to be the fulfillment of a prophecy.
When he realises that he may in fact not be god it occurs to him that all the evil things he has done were, well...evil. Instead of a Heel Face Turn he decides that life as a mortal is not worth living, and that he will take Grace with him.
Saundra: Do you ever worry that we're playing God? Dr Pegasus: Not really. At some point, we definitely stopped playing.
Heat Man from In Wilys Defense, who gets so full of himself that Sphere, the ''actual'' God, has him dragged to Paradise to have the Angel of Destruction, Magdelena, tortured just to get him to shut up about it. It didn't work.
Black Mage's power seems to be unstoppable now killedtwo of his teammates and WhiteMage. Also, he long before considered himself destined to crush that petty world he lives on since he is a nexus of destruction... and stuff.
After looking into the datasphere, Red Mage himself states that his goal is to use his new found infinite knowledge to dethrone the gods and to make the world in his own image.
In Errant Story, a half-elven mage named Meji embarks on a quest to do this as a school project (due to a convoluted backstory that made it her only option for graduating magic university). She seeks to become the single most powerful mage in existence by absorbing the energies of Anilis, believed to be one of the two elven creator gods. Another half-elf mage named Ian beats her to it becoming a very powerful and very insanePhysical God bent on genocide. She later absorbs Senilis, the other elven creator god
Vaarsuvius, after hir Deal with the Devil, has a borderline case of this. S/He ends up trying to destroy Xykon singlehandedly and actually does a lot of damage to him, but mostly just pisses him off.Lampshaded(like most everything in the comic) by the Three Fiends — one of them warns V that the soul splice tends to do this (it's later stated that was just a half-truth aimed at lowering V's inhibitions in order to actually invoke the trope).
In Problem Sleuth, one of Pickle Inspector's clones ascends to Godhood using his pure power of imagination. In somewhat of a subversion though, Godhead Pickle Inspector would only then respond to a command to "fondly regard creation" or something suspiciously similar (such as "crustacean"). Unless the integrity of the universe itself is menaced. DEUS EX SEWING MACHINA
In Homestuck, Karkat addresses John as a wrathful God who despises him after helping to create his universe. What he doesn't realize is that due to weird time shenanigans, from John's perspective they've been talking for a long time and are already friends.
For double irony points, John has, by this stage, gone "god-tier", essentially making him more godly than Karkat. Not that he makes a huge deal of it.
Then come Becquerel's Reality Warper powers, that several people have acquired through various means. Dream Jade notably is said to have "ascended to doghood". And now to dog-tier.
Fans!: Subverted in Book 2, with General Maximiliana.
In Fafnir The Dragon, Edward Catheter invokes this trope after drinking the blood of the titular dragon. However, since he was supposed to bathe in it, not drink it, the firey blood of Fafnir helped to kill him.
In Zodiac, Nightmare considers herself and other superpowered whasnames to be gods because of their powers.
In The Beast Legion, Dragos proclaims himself as a God the will purge the light at the end of Issue 2.
Completely and soul-touchingly inverted in Brother Linnaeus' arc, when the Gragum chief asks Quentyn if he is God...then asks why God seems to have abandoned the Gragum. Quentyn's "letter delivery" for them is especially touching.
Later on, invoked twice by Quentyn during his Badass Boasts, as he refers the Gragum Shaman's claim in both of them.
