Cerkonos

Cerkonos is the headmaster of the Fire Ashari in Pyrah, and one of the guardians of the portal from the Material Plane to the Elemental Plane of Fire. As an NPC, he is portrayed by Matthew Mercer.

Description
Cerkonos is a human with a thick, sturdy build, very dark skin, long jet black hair, a square jaw, and coal-black eyes. He stands about a foot and a half taller than Keyleth. When he first appeared he was shirtless, with brass-colored bracers and long, billowing maroon pants bearing gold trim and designs.

Background
Not much is known about Cerkonos. As headmaster of the Fire Ashari, he likely completed an Aramente earlier in his life and may now have a greatly extended lifespan as a result.

Keyleth's Aramente
Cerkonos guided Keyleth through the fire trial of her Aramente. He and two other druids were waiting to test her in the Elemental Plane of Fire, turning into fire elementals and challenging Vox Machina to a battle. Upon Keyleth's completion of the trial, Cerkonos gifted her with a Sparkstone, to use as she saw fit.

Pyrah's Destruction
At some point near the time Thordak escaped from the Elemental Plane of Fire, Cerkonos lost his left arm.

Sealing the Rift
Cerkonos led the Fire Ashari's efforts to close the rift to the Elemental Plane of Fire, which they did with the help of Vox Machina and Gern Blanston.

Rebuilding Pyrah
In, Cerkonos began regrowing his left arm.

Trivia

 * Cerkonos is the second character featured in Critical Role missing a hand, preceded by Anna Ripley and followed by Tyriok Gadsworth and Shale.  (Victor is missing his fingers on his right hand, but he still has the actual hand.)