Gods were beings of immense power in the religions and mythologies of many species. The powers, abilities and appearances of the gods varied from culture to culture. Some considered transcendental beings gods, due to their power.
The Time Lords themselves were considered gods by some cultures. (TV: The End of the World, Underworld, COMIC: Omega) However, the Fourth Doctor, when asked directly by Idas if he was a god, hesitated briefly and answered no. (TV: Underworld)
Indeed, some Time Lords worshipped gods of their own, the Eternal Menti Celesti, although this was controversial on Gallifrey. (PROSE: Happy Endings) The Second Doctor once offered a silent prayer to "the gods of his own people", (PROSE: The Murder Game) but the Tenth Doctor later claimed that he didn't believe in any specific god, although admitting that had met a number of beings who claimed to be gods. (TV: The Satan Pit) The Twelfth Doctor once pointed out that real Gods would "never actually show up". (TV: The Girl Who Died)
Human gods
The humans of Earth and their colonies had many gods from their many cultures. Most of these gods turned out to be aliens or other advanced beings.
The Celts believed in multiple gods. (AUDIO: The Wrath of the Iceni)
Cessair was worshipped as Cailleach for thousands of years. (TV: The Stones of Blood)
According to the Third Doctor, the Dæmons inspired horned gods throughout history, including the Egyptian god Khnum. (TV: The Dæmons)
The Immortals were many of the gods worshipped around the world. (PROSE: Deadly Reunion)
Kronos was regarded as a deity by the Greeks and Atlanteans. (TV: The Time Monster, PROSE: The Quantum Archangel)
The Latter-Day Pantheon was a group worshipped in New York in 1965. (PROSE: Salvation)
Light was worshipped as the Burning One by Nimrod's tribe. (TV: Ghost Light)
The Osirans Sutekh and Horus were Egyptian gods, (TV: Pyramids of Mars) as were Scaroth, (TV: City of Death) Field Major Styx ("Sontar"), (COMIC: The Gods Walk Among Us) Jane Templeton ("Thoth"), and Antak ("Amun"). (AUDIO: False Gods)
A werewolf was worshipped by the Brethren as a god. (TV: Tooth and Claw)
Xoanon was worshipped by the Sevateem and the Tesh. (TV: The Face of Evil)
A Dalek was believed to be the Bronze God in ancient Britain. (AUDIO: Living History)
In circa 100,000 BC, (PROSE: The Eight Doctors) Earth's sun Sol was worshipped by a tribe of cavemen who called it Orb. (TV: An Unearthly Child)
In the year 1500 BC in ancient Greece, Hangle-Wang Slitheen from the 347th century were mistaken for gods by the Greeks. (PROSE: The Slitheen Excursion)
The ancient Romans worshipped gods of commerce and the mountain and had household gods. Some of the Roman gods included Venus and Vulcan, while the Tenth Doctor and Donna Noble were worshipped by one family as household gods. The Pyroviles beneath the Roman city of Pompeii were believed to have been gods of the underworld. (TV: The Fires of Pompeii)
The Vikings worshipped the god Odin. (TV: The Girl Who Died)
Other gods and goddesses
Many other races had gods of some kind, many of them living beings.
The Doctor was referred to as "the lonely god" in the legend of the Face of Boe's final prophecy, (TV: New Earth) and was worshipped in absentia as "the god of time" by a Roman family after rescuing them from the destruction of Pompeii. (TV: The Fires of Pompeii)
The Time Lords were originally thought to be gods by Minyos, Klist and Plastrodus 14, but they later fell out of favour. (TV: Underworld, PROSE: The Quantum Archangel)
Blon Fel-Fotch Passameer-Day Slitheen considered TARDISes to be "the technology of the gods". The Ninth Doctor responded, "Don't worship me. I'd make a very bad god. You won't get a day off, for one." (TV: Boom Town)
The Dalek Emperor, sincerely believing himself to be a god, specifically "the God of All Daleks". He was worshipped as such by the Daleks he had created from deceased humans to resurrect his race after escaping the Last Great Time War. These specific Daleks even had a concept of blasphemy. (TV: The Parting of the Ways)
The Optera believed the Menoptera to be gods. (TV: The Web Planet)
Aggedor was thought to be a god by the Peladonians. (TV: The Curse of Peladon)
The Deons believed in Ti and thought the Dodecahedron was his gift. (TV: Meglos)
The Worldsphere God was a machine who watched over the People. (PROSE: The Also People)
Kroll was worshipped by the Swampies. (TV: The Power of Kroll)
The Nimons' modus operandi was for an individual Nimon to set himself up as a god to a given species, claiming to be one-of-a-kind, thus clearing the way for a large-scale invasion. Many of the inhabitants of Crinoth and Skonnos thus once worshipped "the Nimon" as their deity. (TV: The Horns of Nimon)
A related Minotaur-like species also set themselves up as the gods of many races, feeding on faith and worship. On one world, the natives expelled a Minotaur they had formerly worshipped when they realised that it was a fraud. (TV: The God Complex)
The Kaleds had a god of war. (TV: The Satan Pit)
Ancient Gallifreyans worshipped their moon Pazithi Gallifreya as a virgin Goddess. (PROSE: Cat's Cradle: Time's Crucible)
The line of Pepins ruled as gods. Pepin VII abdicated, leaving Frobisher as a god in his place. (AUDIO: The Holy Terror)
The Sisters of Plenitude had a goddess named Santori, and invoked her during bad times. (TV: New Earth, Gridlock)
Thoueris was mistaken by the Egyptians for a god. (COMIC: The Power of Thoueris!)
Balor was worshipped as a god by the Cynrog. (PROSE: The Nightmare of Black Island)
The Jaftee sequentially worshipped a number of gods, including Donna Noble who they called the "Ginger Goddess". They made a habit of trading in old religions for new ones. (PROSE: Shining Darkness)
The Tenth Doctor told Jack Harkness that if a Time Lord took on the Bad Wolf entity, they could become "a vengeful god". (TV: Utopia)
The inhabitants of Sto worshipped a god known as Vot. (TV: Voyage of the Damned)
After K9 Mark I liberated the Anubians from the Huduct, the Anubians worshipped him as a god. (TV: Curse of Anubis)
Akhaten was a celestial object that was described as a "parasite god" by the Eleventh Doctor, represented by the mummy. (TV: The Rings of Akhaten)
The people of Ribos believed that their planet was a battleground to a war between Ice Gods and Sun Gods, producing the turnover of the seasons. (TV: The Ribos Operation)
The people of the volcanic planet Sarn worshipped the fire-god Logar, actually Trion volcanologists in a thermal protection suit. (TV: Planet of Fire)
The Guardians of Time were, together, the Six-Fold God. They were the masters of reality, each being responsible for a sixth of the Universe. (PROSE: Divided Loyalties, The Quantum Archangel)
An Ood on Krop Tor under the possession of the Beast claimed that “the Beast and his armies shall rise from the pit to make war against God”. (TV: The Impossible Planet)