Glenn Groff, a non-human from Ashwhite known by the nicknames Thickhead or Mule, participates in the Cosmo Academy final exam aboard the derelict spaceship *Esperanza*.

He presents a bald appearance and exhibits a stubbornness that fuels his nicknames, reflecting persistent determination rather than lack of intelligence.

Thickhead proactively volunteers for tasks, showing dependability within the group. He maintains a calm, practical focus on problem-solving during the crew's survival efforts.

His specific duties involve assisting with maintenance in the engine room, which faces a crisis from rapidly growing, ship-threatening conductor vines. Addressing this threat forms part of his contribution to the team's survival.

Available materials provide no detailed background on his history, Ashwhite culture, or personal motivations beyond passing the exam. His character development throughout the narrative remains minimal, defined by his consistent, supportive role facing collective challenges.