Dum-E was a robotic assistant in Tony Stark's lab.
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.
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. Afterward, Dum-E was tasked to clean up the mess that the new element's creation caused.
Over time Tony built several similar robot assistants to help him in his workshop as well. While Tony was testing the Mark XLII, he gave the original Dum-E a dunce hat for something it had done. When Tony's house was destroyed, Dum-E and the other robots were destroyed as well. When Tony returned to the ruins of his destroyed home, he took the remains of the original Dum-E and parts of his workshop to repair and rebuild it.
- 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.