My favorite obscure D&D god, though, is Wastri, whose bizarre portfolio stirs the imagination: self-deception, bigotry, human supremacy, and amphibians. There are shades of Lovecraft's Deep Ones in how the Hopeful of the Hopping Prophet slowly transform into grey-skinned frog-men and associate with bullywugs (who likewise become more humanlike), but the deity is rather unique in his scope and desires, and I can't find any basis for it in anything else. I like it when fictional gods are messy; you see it a lot in real world pantheons, like how Poseidon is also a horse god.
Humanity and its supremacy are already great domains for a Lawful Evil god- see also my second favorite D&D god, Zarus- but the inexplicable amphibious angle makes him a bit more interesting and nuanced than the Burning Hate. The in-universe lore is that amphibians are respected because having a refuge when one of your habitats becomes dangerous is resourceful, and resourcefulness and adaptability are the greatest traits of humanity (another oddity; most Law/Chaos systems associate adaptability and change with Chaos, but Wastri is Lawful Neutral or Evil). There's also the fun contrast between Zarus's too on-the-nose "human supremacy, racial purity, imperialism, and primacy of the perfect human form" angle vs. the nearly transhumanist Wastrian end goal of amphibious frog-men.
Furthermore, Wastri strangely desires goblinoids, orcs, and bullwugs to survive as slave races (yes, Bullywugs worship a god that wants them as a slave race, rather sad), while calling for the extermination of the standard non-human PC races, despite these generally being allied with humans.
Wastri's influence also explains D&D's strange idea that frogs are disgusting monsters- see bullywugs, grung, banderhobs, slaadi, and the froghemoth. At least grippli are bros.
Edit: also, the signature priest of Wastri is a cleric/monk that is described as "hopping" into battle, which, fuck yes
