_Stargate_, the original movie: Only [Ra][1], Egyptian God of the Sun, was in it. The credits to the film also listed Anubis and Horus as temple guards to Ra, but they are not named on screen, do not appear to be the same race as Ra, and were supplanted by Goa'uld in the shows.
Everything else:
- All the [System Lords][2] were mythological figures in real life
- Egyptian
- Anubis, Egyptian god associated with mummification and the afterlife
- Apep and Apophis appear to be the [same being][3] in mythology (an evil god, the deification of darkness and chaos), but have been split up into two separate System Lords for Stargate
- Bastet, Goddess of cats, and the sun and the moon
- Hathor, Goddess of love, beauty, motherhood, foreign lands, mining, and music
- Heru'ur has no direct equivalent in mythology, but takes the place of [Horus][4] in Stargate.
- Isis, Goddess of motherhood, magic, and fertility
- Osiris, Egyptian God of the Afterlife. In a female host in Stargate due to unfortunate circumstances
- Sokar was originally an [Egyptian Falcon god][5], but at some point before appeared in Stargate, that Goa'uld took the part of the devil.
- Japanese
- [Amaterasu][6], Goddess of the Sun and the Universe in the Shinto religion.
- Greek
- Ares, God of War
- Cronus, Titan
- Roman
- Egeria, water nymph
- Celtic
- Camulus, God of War
- Hindu
- Kali, Goddess of Destruction
- Nirrti, Goddess of Death and Corruption
- Babylonian
- [Belus][7] in a Greek text in a Babylonian context refers to the god Bel Marduk, who is worshipped as the God of War (among other things).
- [Marduk][8], God of Creation. This does not appear to be the same Marduk as Belus/Bel Marduk.
- African
- Moloc, which has the much more common spelling of [Moloch][9], is an Ammonite god, and was worshipped by the Canaanites, Phoenician, and other cultures in North Africa.
- Olokun, an Orisha in the Yoruba religion. The [Orisha][10] are spirits/deities that reflect one aspect of god.
- Irish
- [Morrigan][11] appears to have been a goddess of battle, strife, and sovereignity, although she was not referred to as a goddess in the mythology.
- Slavic
- Svarog, [Possibly][12] god of celestial fire and blacksmithing.
- Chinese
- Yu-huang Shang Ti, the [Jade Emperor][13].
- Misc/Uncertain of locality
- [Ba'al][14] is a title with many possibilities, but an alternative spelling I've often seen is [Baal][15], a demon who is one of the seven princes of Hell.
- [Ishkur][16], also known as Adad and Hada, is a god in the Babylonian-Assyrian pantheon.
- Kur is labeled as "Sumerian and Assyrian Dragon/Dragon Lord" on the Stargate Wikia, but his place in mythology is a [bit more complex][17]. Kur is 1) a mountain or mountain range, 2) possibly the Sumerian underworld, or related to it, 3) possibly an Anunnaki, or 4) a snake-like dragon. It seems to depend on the era.
- As I mentioned in one of the comments, even (at least some of the) Goa'uld who were not System Lords came from history/mythology:
- Imhotep was a minor Goa'uld who appeared in just one episode. In reallife, [Imhotep][18] was a chancellor who was promoted to divinity after his death.
- Next are the Asgard. [Almost all the named ones][19] come from Norse mythology - which makes sense, as in-series, the Asgard inspired the Norse myths.
- These are the ones that have a directly copied name:
- Aegir
- Fenrir
- Freyr
- Heimdall
- [Loki][21], named after the Norse god of mischief
- Thor
- Tyr
- These are the ones I'm unsure of, or have a slightly different name:
- An
- Famrir (Former host to Ra, he was seen for a single scene in the original Stargate movie)
- Hermiod, named after the Norse god [Hermóðr][20]
- Penegal
- Sujanha, who did not appear in any TV series or movie
- Zeus, who did not appear in any TV series or movie. However, according to his [bio page][22], Zeus was originally a Goa'uld in the Greek pantheon. Long after he left, an Asgard crash landed in the vicinity, lost his memories, and took up the name after the humans there mistook him for their former god, Zeus.
- The [Nox][23] appear to be based upon the Greek [Dryads][24], or some similar myth.
- The Ancients aren't anything as a whole, but:
- [Atlantis][25] was a spaceship/city combination that held the most advanced technology the Ancients ever developed.
These two go with the list of Ancients references, but are much more spoilery than any of the above:
>! * [Merlin][26] was an ancient who was originally named Moros. We met him before his ascension, as Moros, in an episode of Stargate Atlantis.<br><br>
>! * [Morgan le Fay][27] was born as Ganos Lal, and like Moros, had ascended and then retaken human form.
[1]: http://en.wikipedia.org/wiki/Ra
[2]: http://stargate.wikia.com/wiki/System_Lord#List_of_System_Lords
[3]: http://en.wikipedia.org/wiki/Apep
[4]: http://en.wikipedia.org/wiki/Horus
[5]: http://en.wikipedia.org/wiki/Seker
[6]: http://en.wikipedia.org/wiki/Amaterasu
[7]: http://en.wikipedia.org/wiki/Belus_%28Babylonian%29
[8]: http://en.wikipedia.org/wiki/Marduk
[9]: http://en.wikipedia.org/wiki/Moloch
[10]: http://en.wikipedia.org/wiki/Orisha
[11]: http://en.wikipedia.org/wiki/Morrigan
[12]: http://en.wikipedia.org/wiki/Svarog
[13]: http://en.wikipedia.org/wiki/Jade_Emperor
[14]: http://en.wikipedia.org/wiki/Ba%27al#Deities_called_Ba.CA.BFal_and_Ba.CA.BFalath
[15]: http://en.wikipedia.org/wiki/Baal_%28demon%29
[16]: http://en.wikipedia.org/wiki/Ishkur
[17]: http://en.wikipedia.org/wiki/Kur
[18]: http://en.wikipedia.org/wiki/Imhotep
[19]: http://stargate.wikia.com/wiki/Asgard#Known_Asgard
[20]: http://en.wikipedia.org/wiki/Herm%C3%B3%C3%B0r
[21]: http://www.gateworld.net/wiki/Loki
[22]: http://stargate.wikia.com/wiki/Zeus_%28Asgard%29
[23]: http://stargate.wikia.com/wiki/Nox
[24]: http://en.wikipedia.org/wiki/Dryads
[25]: http://en.wikipedia.org/wiki/Atlantis
[26]: http://en.wikipedia.org/wiki/Merlin
[27]: http://en.wikipedia.org/wiki/Merlin