Morte

Morte, born Mortimer Rictusgrin, is a floating skull, and actually not a Mimir.

Background
Morte is floating around the Wasteland, having landed in the Fallout world after accidentally going through a portal in a brothel window in Sigil, the City of Door.

Appearances
Among all Fallout games Morte appears only in Fallout Tactics: Brotherhood of Steel. He can be seen in a special encounter also named Morte.

Behind the scenes

 * It's an important character and a potentiel companion in the game Planescape Torment made by Black Isle Studios. The lead designer was Chris Avellone, a major developer of the Fallout universe.
 * Morte is Latin for death if one was to address death directly.