Zarekos was in the process of ascending to godhood when Mercury encounters him. This grants him, an already quite powerful vampire, additional powers, such as the ability to revive once when killed in battle.
To understand everything important there is to know about the universe, apply that knowledge to become omnipotent, and use that power to rewrite reality because I have some objections to the way it works now.
There are fanfiction roleplayers who fall under this trope. They really love God Moding, even if it's a huge annoyance to others. Can you say "Mary Sue"?
In Divine Blood, this is averted as Tessa Testarossa became the first Ainur more about ensuring the psychological and spiritual survival of her people against things like this fic's version of Kodachi Kuno and to serve as a message to the Gods and Demons that humanity can't be pushed around anymore. She still insists on being kept in the normal chain of command and suggested that having a full Ainur division would be a mistake and point of vulnerability.
In A:TLAR, the interpretation of the Avatar (of the series Avatar: The Last Airbender) is a bit different. The Avatar Spirit is er, was a resident of the Spirit World that aspired to create a physical world that would teem with life. Once it had crafted the earth and humanity, it blessed humanity with a genetic trait that would allow a being to manipulate the molecules of elements, otherwise known as bending. The gift of bending divided humanity into four peoples that were isolated from each other, the Air, Water, Earth and Fire civilizations. It selected one airbender to be its host, so that it could teach the Air people the principles that it believed humanity needed to be taught. Once its host had died, it began a cycle that continued for generations by choosing to inhabit one of the Water people next, then one of the Earth people, and lastly one of the Fire people. Once this cycle had finished, it repeated itself. After each cycle completion, the role of the Spirit is taken over by the soul of one of the last generation's hosts, i.e. after the first cycle, the spirit of the first air host became the new Avatar, then after the second cycle, the spirit of the second water host became the Avatar, etc. Although the Spirit is a full-on Reality Warper, the hosts are not. The hosts can only have limited access to the Spirit's massive power reservoir by going into the Avatar State, which can only be achieved by severing all of one's earthly ties, also known as the Transcendence ritual. Beings that take the role of the Spirit and have undergone Transcendence have difficulty relating to entities of the physical realm, which can eventually go from bad to worse as (Foreshadowing) the Spirit loses all empathy for humans and embodies A God Am I. Problem is that theory is jossed by canon.
In the My Little Pony: Friendship is Magic/Discworld crossover Binky Pie, Pinkie Pie ends up inspiring a "Church of the Pink Pony of Death" while helping as Death's new assistant. Since Gods Need Prayer Badly is in full effect on the Discworld, Pinkie Pie eventually ends up ascending to godhood. Complicating matters is the fact that she had previously been standing in for Death after he got trapped in Equestria due to a magical mix-up...
The Immortal Game: Ignoring the fact that most of the main villains and one of the protagonists are actual gods, the story ultimately has a subversion of this trope in the case of Twilight Sparkle. After tapping into the full power of the Elements of Harmony, she becomes a Physical God so powerful that only Titan himself is able to knock her down — and she is horrified by it, deciding that nopony should have that much power.
And then a double subversion when she absorbs the full powers of the goddess Harmony herself during the Final Battle. She admits that by all definitions of the word, she is a god now.
Luna used to think like this (though to be fair, she is a god), to the point that she was offended that Her Father actually cared about the lives of mortals. Fortunately, He then put her through Break the Haughty, followed by her later actually spending time as a mortal, which changed her views.
Twilight Sparkle in Pages Of Harmony, full stop. After extracting the essence of the Elements of Harmony from her friends and analyzing their signatures, she intends to use her research and magic to eradicate all beings in the universe - and multiverse, if it exists - that don't have the genetic capacity for harmony, letting only the ones she judges as worthy being allowed to live, intending to train the survivors. And if that weren't enough, she intends to make herself immortal to keep her "perfect reality" stable and orderly according to her wishes for as long as she can—which, in her mind, is eternity.
As if that's not enough, in Chapter 12, at the end of the first story arc, she absorbs the essence of all the Elements of Harmony and becomes an ethereal alicorn-like creature, declares herself to be "Harmony Incarnate", and performs a memory-alternation on Ponyville's population so they believe she's their Empress.
Diaries of a Madman: Discord declares himself as one several times, and gets extremely irritated whenever anyone else refers to Celestia and Luna as gods, viewing them as pretenders.
In Fallen King, Maximillion Pegasus thinks of himself as a god after defeating Yugi, with plans to rewrite reality in his image.
Initially averted in Death Note Equestria, as Twilight views herself as a Necessarily Evil murderer, but doesn't view herself as a god. However, after L's death at the end of the second season, she dives right into this — she decides to set up Kira as a mythological figure of evil in order to scare anyone out of performing evil ever again, while also leading the "resistance" against Kira. She figures that such a position on both sides would make her a goddess.
Discord proclaims himself one in The Non-Bronyverse AU story The Breaking of a Non-Brony. TD also uses this in the AU story TD the Alicorn Princess, but only to threaten Blueblood with it.
In Ultraman Moedari, Mater Mundaram pretty much forces this on one of the protagonists.