(From Planescape: Torment Videogame - 1998):

Morte is a talking skull. His sole weapon seems to be his mouth, whether by taunting or biting. He seems to be along for the ride, whether you want him around or not.

You are somewhat curious as to how he is able to float around.

(From Planescape: Morte's Planar Parade - 2023):

Planar travelers often find mimirs invaluable in learning about reality and avoiding doom at the hands, claws, fangs, tentacles, proboscises, ovipositors, and other appendages of the multiverse’s countless predatory and lethally grumpy inhabitants.

Morte, however, isn’t a mimir.

A floating skull with a penchant for speaking his mind and claiming expertise, Morte is one of Sigil’s many unique inhabitants and an accomplished explorer of the planes. For the right amount of coin or a future favor, Morte is quick to offer his advice, insights, and commentary on the many inhabitants of the planes. This book contains useful data gleaned from Morte’s stories and ramblings. Still, the planes are vast and varied, and what Morte experienced as true might not match all circumstances. Reader beware.

"Morte. A self-professed 'famous' planar traveler who often poses as a mimir to-"

- Partial mimir response on the subject "Morte"

“Whoa, hey, hey! Zip it there, bud! I don’t know who got you a defective mimir, Chief, but I’ll tell you what’s what from here out.”

- Morte

(from Planescape: Turn of Fortune's Wheel - 2023):

A human skull floats nearby. It bobs impatiently, watching you with slate-gray eyes that remain in its lidless sockets.

The skull notices you’re awake and greets you with a nasal voice. “Hey, Chief!”