Grim is a skeleton Dog owned by Dan. He was first a gift to Dan from Dr. Trayaurus. Later, he was revived into a Skeleton, recurring in Mod Showcases, Custom Mod Adventures and other videos ever since. And is now here today.
In the GRIM'S TALE | How I Met Grim The Skeleton Dog | Minecraft video, Dan was given a gift from Trayaurus on 8th November for his "Birthday". From that point on, Grim has been Dan's pet Dog. But, a "Few years later", Trayaurus made a "Cloning Machine", and Grim was the first test subject, but after this he was just a pile of bones. There where some scenes how Dan try to play with him. Later, Trayaurus revived him as the skeleton dog with his rivival machine. He became a recurring character after that. Grim also protects Dan from harm in some Mod Showcases.