Clarence was buried in the "ne'er-do-well" section of the Cemetery under a gravestone that reads "R.I.P. Some Donkus." He became a ghost who had no memory of his former life. Clarence met Ghost Princess and immediately defended her when Boilbee was making her upset. He then took her to see the Spirit Waves. Finn and Jake figured out it was Clarence who killed Warrior Princess (now Ghost Princess) by matching the remains of a dagger handle in Clarence's grave with the tip of a dagger in Warrior Princess' remains. Ghost Princess almost ascended to the Dead World upon learning how she died. When Clarence couldn't come with her he frustratingly proclaimed that his life was "like a fart." Because these were his last words before he died, Jake remembered who the man at the mart was, resulting in Clarence remembering his death. He died by exploding after eating too much cheese. Ghost Princess said that she forgave him, and he was then able to ascend along with her.
In his ghost form, Clarence has the same type of skin tone of all other ghosts on the show, however, compared to Ghost Princess, he has a darker blue coloring. He has long hair that trails behind him and wears a headband with antler ears attached, that may be part of his body. From one of his antlers, a small sword hangs. Clarence also wears a jacket.
When he was alive, Clarence looked very similar to his ghost form, the only changes were that he had green skin and wore pants. He is also shown in battle armor. In both forms, he wears his signature headband.
- Clarence's last words in his life, "My life is like a fart," is a play on the more conventional saying, "My life is like a farce."
- "Donkus" is not his surname. When Clarence was buried, his name was unknown, so they labeled him as "Some Donkus." This is similar practice used in Canada and the United States when an anonymous individual is called "John Doe" or "Jane Doe." 
- It is not known how long Clarence lived after the battle in which Warrior Princess was killed. The battle seems to take place amid the ruins of highways and wind turbines. The Squeez-E-Mart seems to be located in the same general area as the battle but during a period in the Land of Ooo contemporary to Finn and Jake. It is likely that Clarence was living in the area for quite sometime after the battle before Jake witnessed his death.
- Clarence's skeleton has a large hole in its ribcage, this is likely due to him exploding. Likewise, there are strange protrusions on the sides of his head where his "antler headband" fit around his head, showing that while the headband may or may not have been part of his body, the antlers were.
- In the original storyboard for the episode, posted online by Frederator Studios, a flashback showed Clarence asked Warrior Princess to run away with him before the final battle, but she refused, stating she had to fight for her kingdom. In this version, Clarence died not as the result of exploding, but by slipping on Softy Cheese that had spilled on the floor.