Grim

Grim, the Skeleton Dog
Grim is Dan's closest friend and lives with him and Dr. Trayaurus in the lab. Grim is a skeleton dog, which means that every time he dies, he will be revived. He appears in the Player Statue World.

How Grim Should Have Flesh And Blood
Grim was given as a present to Dan from Trayaurus for his birthday. Grim accompanied Dan in many adventures, including mining, mob slaying, etc. One day,Trayaurus offered Dan to clone Grim so they could have more fun with a new dog friend. When Dan pushed Grim into the Cloning Machine Prototype and Trayaurus turned it on, the machine went extremely wrong, killing Grim and turning him into a pile of 7 bones.

Revival as Skeleton Dog
After Grim's death, Dan didn't talk to Trayaurus for weeks. One day, Trayaurus offered to bring Grim back in his Revival Machine Prototype. Grim was brought back, but as a Skeleton Dog, so he can't die. To this day, Grim, Dan and Trayaurus are best friends and live in the lab together.

Trivia
Grim the Skeleton Dog can not be downloaded, so people made texture packs that have the look of Grim like he does in TheDiamondMinecart series.