"Only God should have the power to be in all places at all times."
― Roland (Jumper)
"Listen, even as we're talking, I'm there for old and young, innocent and guilty, those who die together and those who die alone. I'm in cars and boats and planes; in hospitals and forests and abbatoirs. For some folks death is a release, and for others death is an abomination, a terrible thing. But in the end, I'm there for all of them."
― Death of the Endless (DC Comics)
"Where is it?"
"It is everywhere. It is everything. Its scales glisten in the bark of trees, its roar is heard in the wind, and its forked tongue strikes like, like..."
"(lightning strikes a nearby tree)"
"...whoa! — like lightning! — yes, that's it."
― Arthur and Merlin describing The Dragon (Excalibur)
Omnipresence is the property of being present everywhere and anywhere.
User is present everywhere at the same time, referring to an unbounded or universal presence. It is related to the concept of ubiquity, the ability to be everywhere and nowhere (at once).
Users are usually an incorporeally present like an invisible force of being that's literally everywhere yet unseen, felt or heard unless they wish to be interacted with, positively or negatively effecting any and all things in the universe by the users presences and will.
Eternity (Marvel Comics) is the embodiment of Time.
Infinity (Marvel Comics) is the embodiment of Space.
Death (Marvel Comics)
The Living Tribunal (Marvel Comics) is the overseer and embodiment of the Marvel universe.
Schrodinger's (Hellsing) ability of being everywhere and nowhere extends even to very subjective realms.
ZeedMillenniummon (Digimon) is able to fly freely through space and time.
Lord English (Homestuck) exists in all timelines, even before his birth, and is represented as being "already here" even by the author.
The Master Emerald (Sonic the Hedgehog) is transcendental object that exists simultaneously in all time lines across the time-space continuum.
The Time Eater (Sonic the Hedgehog) is an almighty entity of time.
Solaris (Sonic the Hedgehog) is a god of time and transcendent life form that is omnipresent throughout time. The only way to defeat him is to attack him in the past, present, and future simultaneously.
The Elder God (Legacy of Kain) is "eternally present, here and everywhere, now and always."
After supposedly dying in a Lutece field "accident", Robert and Rosalind Lutece (Bioshock Infinite) became scattered across the probability space, allowing them to exist through-out time and space within their shared multiverse.
After the machine inhibiting her abilities was destroyed, Elizabeth Comstock (Bioshock Infinite) became omniscient and omnipresent within her multiverse through all of her alternate counterparts.
Spenta Mainyu (Valkyrie Crusade), the watcher of all creation.
Mr Burt/God (The X-Files) displaying his omnipresence by appearing as the entire city.
The Endless (Vertigo/DC Comics) exist everywhere their domain is represented.
The Presence (DC Comics)
As Herrscher, Ain (Elsword) exists everywhere and nowhere.
As Death Embodiment of Runeterra, Kindred, the Eternal Hunters (League of Legend) can appear at everywhere when a life is near end.
Yog-Sothoth (Cthulhu Mythos) Opener of the Way, Beyond-One, All-in-One, One-in-All, is coterminous with all time and space.
Apakht/SCP-001 - The Lock (SCP Foundation) describes the concepts of time, space and even reality as just meaningless, existing everywhere within and outside of all of it.
SCP-3999 - I Am At The Center of Everything That Happens To Me (SCP Foundation) happens to be everywhere and nowhere at all times.
SCP-4755 - Mouth Moods (SCP Foundation) completely encompasses reality and beyond with all concepts within it.
An omnipresent map can be confusing.
Lucy’s reply to “Where is she?” when she reaches 100% brainpower.