Quillgin

Quillgin is an evil elf and the main antagonist who only appeared in the Regular Show half hour special The Christmas Special.

Confronting Santa on his sleigh
When Quillgin uses Santa's sleigh, Santa comes to stop Quillgin that he cannot use the sleigh without permission. Quillgin tries to open the present that hypnotizes a characters eyes, but Santa stopped Quillgin by telling Rudolph the Reindeer to use his red nose to shoot a laser in order to keep the present from being used. Quillgin shoots Santa and he falls of he sleigh, but he still survives.

Quillgin's Flashback
Quillgin worked with the other elves in Santa's Workshop, but he turned evil and made a present by using dark magic. Quillgin's present turns people evil when it is opened. Santa ordered the other elves to stop Quillgin's life work.

Confrontation in the Volcano
When Mordecai, Rigby, Muscle Man, Pops, and Skips enter the volcano, Quillgin tries to stop the gang in the pinball room with his henchmen. His henchmen fall off the bridge, but Quillgin survives.

When the gang is confronting Quillgin in the lava pit, Quillgin shows the destruction of Christmas to the gang. The gang sees dynamite bundles on Christmas images, including Earth. Quillgin starts to confront Mordecai and Rigby until he and the magical present fall into the lava, leaving both of them destroyed.