Deneir

Deneir
Alignment	Neutral Good
Divine Rank	Lesser God
Pantheon	Faerun
Portfolio	Maps, Symbols, Images, Knowledge, Art, Literature
Domains	Good, Knowledge, Protection, Rune
Home Plane	House of Knowledge (Outlands or Mechanus)
Worshippers	Historians, Librarians, Sages, Students, Scribes
Favoured Weapon	Dagger

Deneir is the bitch of Oghma, the God of Knowledge... so where Oghma gets all the glory as the god of invention, inspiration, instruction manuals and intellectual property laws: Deneir is the one who does all the manual labour and actually writes that shit down.

You might think him a minor minion of little note in a pantheon that spans pretty much every variation on a conceivable theme and has several deities with egregiously overlapping portfolios; and you'd probably be right: Deneir contributes very little to the evolution of the Forgotten Realms, except when he's placed under the care of R.A. Salvatore.

Deneir's two major contribution are: his Chosen and his last stand to try and halt the onset of 4e.

When Shar and Cyric colluded to kill Mystra and precipitated the events of the Spellplague and essentially upending the table of magical powers, Deneir apparently disappeared as well, not answering prayers or granting spells.

However it was later discovered that he had not died in the upheaval as had so much of the rest of the pantheon, but he had set himself the task of attempting to rewrite The Weave. Which was something only Mystra could have done, and was probably outside of Deneir's remit, but he tried anyway. And for the years of the Spellplague this underdog of a deity was trying to keep things from becoming any worse.

Deneir's final "gift" was to write himself into the weave as a means of saving it, utterly obliterating himself in the process, but would allow magic to function again without turning it's users into insane, drooling, mutants.

We could take that as the fluffy excuse for 4e in general and why spellcasting went all MMORPG on us for no good reason, but we can't blame Deneir for what our favourite game would become, since the decision was made at the corporate level and not by the authors. So Deneir really was the failed hero of the setting, who gave his last gasp to keep it alive.

...then 5e reconned it, so it never happened... back to the writing desk with Deneir.