- "For lack of another option, Dum-E is on fire safety. And if you douse me again when I'm not on fire, I'm donating you to city college."
- ―Tony Stark
Dum-E and U are the robots Tony Stark uses as assistants in his workshop. He made Dum-E in his father's workshop. While Dum-E is generally used to help with Tony Stark's creations, U is used to do the registration of Stark's work using a video camera. They had even saved his life, yet Stark constantly gets angry at the robots. Dum-E and U had helped make some of Stark's armors.
After Tony Stark escaped from his captivity, Dum-E and U helped him make the Mark II. When Obadiah Stane decided to steal his Arc Reactor, Stark 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 Stark's life.
After Stark 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. Afterwards, Dum-E was tasked to clean-up the mess that the new element's creation caused.
- Dum-E's and U's names are a play on the words "Dummy" and "You" respectively.