Zaxis

Zaxis is a hezrou bound to the service of Ammon Jerro.

"'Foul to the eyes and downright horrific to the nose, this gargantuan terror is not of this world. Sword-length spines line this creature's scaled hid. Its arms are thicker than the body of a mortal man and end in massive fists with razor-sharp claws. Wicked teeth line the beast's massive jaw and, judging by the size of its torso, its stomach likely has room to consume you, your companions and your gear in one meal.'"

Official Campaign
Zaxis was one of the many powerful fiends Jerro had bound to him in service, and probably the least intelligent of them all. And despite the brutish appearance, Zaxis is actually a she, a marilith that didn't quite make the cut and was demoted as a lower fiend. Her personality is highly simple-minded and vapid, primarily issuing (mostly hollow) threats of dismembering and devouring.

Zaxis was originally summoned by Jerro when he went against the King of Shadows, and like many of her kind wasted no time in ravaging the countryside as they faced the shadows. The party first meets her in the Githyanki caves, whom Jerro brought along with Mephasm to the hideout to retrieve the shards Zeeaire had recovered. Zaxis was trying unsuccessfully to tear down the door to the portal chamber, and could easily be tricked by the PC into being banished for failure. Zaxis was seen again as one of the six bound in the Haven, and was not at all pleased to see the party again, sending hezrou minions to attack and refused to help open the way to Jerro's laboratory.

If the player "helps" out the succubus Blooden, she reveals the Truename of Zaxis, "Bethshiva," revealing her gender, origin, and the fact she is the mother of Baalbison, a balor also bound there. With this true name, the player could force Zaxis to open the gate, and fulfill Hezebel's request of obtaining the true name of Baalbison's mother.

Trivia

 * Zaxis' brief voice-over in a cutscene was performed by Elizabeth Van Meter.
 * Zaxis generally only referred to herself in third person, much to Neeshka's extreme annoyance. With the true name, the PC can try to force her to stop referring to herself in third person, but she fails to carry out the order as she is too dumb to understand what he/she meant by "third person."