Shacktron

The "Shacktron" is a giant robot created during the Weirdmageddon by the survivors of the mentioned event to fight back against Bill Cipher. Its name was coined by Soos Ramirez prior to the start of the battle it took part in.

Physical Appearance
The robot is composed of various objects seen through the series. These include
 * The Mystery Shack
 * Parts of the Gobblewonker
 * Cars