"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."
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 Presence (DC Comics)
The Endless (DC Comics/Vertigo) exist everywhere their domain is represented.
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.