The Naga are one of the monster races of warcraft. They were originally Night Elves^A) that sunk under the sea with their Queen Azshara. After sinking, the energies of the Well of Eternity transformed them into Naga. Or, if you believe the retcon, they were transformed by the Old God N’zoth.^B)
I’d do ‘em ‘cause Naga are hot…but I’m not a scalie.

The Naga Anomalies are really freaking cool conceptually. It’s honestly baffling that they weren’t integrated into the lore. I’m guessing the reason why is due to the whole N’zoth retcon, which really doesn’t mesh with their lore.
So, what is that lore? Well, Naga Anomalies are those Naga who found themselves affected waaaay more by the residual energies of the Well of Eternity than the average Naga. Consequently, they experience more mutations than the average Naga.
So, for example, Naga women can grow more arms…but Naga Anomalies can grow even more arms…or grow tentacles…or learn to squirt ink.
It’s speculated that Naga Brutes are a (half-assed) rehash of the Anomaly concept.

Naga sirens, not to be confused with Sirens or sirens.
All Naga Sirens are female Naga but not all female Naga are sirens. This is a real reversal of the Night Elf hierarchy, as all the spellcasters in Naga society are women.
Sirens are, as far as I understand, just a class of female Naga. They aren’t actually a sub-species or anything.
All the Sirens in WC3 have four arms, which I didn’t know until more recently.

• Naga
• Naga anomaly