Dum-E and U

Dum-E is a robot Tony Stark made in his father's workshop. It has helped him and failed him in the past. It has even saved his life, yet Tony constantly gets angry at the robot. Dum-E has helped make some of Tony's armors. At some point Tony made another Dum-E robot.

Creation
Tony Stark created Dum-E in his father, Howard's workshop. The robot seemed to be of some use so Tony kept it.

Iron Man
When Tony was becoming Iron Man, Dum-E helped him make his suits, including the Mark II and Mark III. When Obadiah Stane decided to steal Tony's Arc Reactor, Tony almost died and went to his garage to get the arc reactor on a mantle that Pepper Potts made for him. He was unable to reach it and gave up, but Dum-E gave it to him, thus saving Tony's life.

The New Element
After Tony learned of a new element discovered by his father, he decided to rebuild the element to fix his current arc reactor. Dum-E helped him make the element.

Mark XLII
Over time Tony made an almost exact replica of Dum-E to help him in his workshop as well.

While Tony was testing the Mark XLII, he gave the original Dum-E dunce hat for something it had done.

When Tony's house was destroyed, both Dum-E robots were destroyed as well. When Tony returned to the ruins of his destroyed house he took the remains of the original Dum-E and parts of his workshop.

Trivia

 * In Iron Man 2, DUM-E can be seen printed on the side of one of the robots, confirming the name.
 * In Iron Man 3, "U" can be seen printed on the side of one of the robots, confirming that it has a name as well.
 * It is a play on the word Dummy.