Poll

Well, as far as I can tell Anansi is an african trickster god in the vein of Loke (Loki), also known as "the Spider".
Gaiman used him in Anansi Boys, and I think in American Gods. And China Miéville used him in King Rat (don't remember if he was called Anansi there, or if he was just used as a template).

Anansi is pre-christian, as are most of the pantheons I've listed here.
It's of course entirely possible that there has been a tribe with a similar name out there, but the spider-god is the only Anansi I'm aware of.

I meant to link you to the Encyclopedia Mythica, but seems I forgot. Here you'll find more gods than you can shake a thunderbolt at, including Anansi.

Vicki, could you be thinking of the Anasazi?

Anansi, is indeed a spider/trickster god from West African mythology; also referenced in Niven and Pournelle's The Descent of Anansi.

Also, my answer is currently flip-flopping between Greco-Roman and 'other' (Egyptian).

Doh!

Can't believe I forgot Ra, Anubis, Bast etc.

*headdesk*!

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Fixed!
And Rindis it seems that you automatically landed on Egyptian, as I moved "Other" down, and Egyptian landed as #9.

I've always been close to the Celtic mythos but also have a very strong liking of the North American Indian mythos. Most especially those dealing with the Anasazi people and somewhat with those what came after (Hopi & Navajo).