There have been a number of domains that have been referred to as the "Fifth Dimension", another/other dimension(s) that exists parallel to Earth-616. There is no conclusive proof that these are the same location or different dimensions all together. For the sake of clarity, they are all listed here.
The first recorded time that Earth interacted with the Fifth Dimension began with a scientist from that dimension named Bolo who was inspired to build an army of robots based on the human race to use as slaves in his home dimension. His first and only creation to this end was the intelligent robot known as Marvex. However, Bolo's mistake was creating Marvex with free will and his creation revolted, killing Bolo. Marvex then breached the barrier between worlds to explore Earth and learn what it was like to be human. He had many adventures on Earth during the 1940s before taking a nap for decades and then flying off into space.
In the modern age a highly advanced society existed in what was classified as the Fifth Dimension. About a decade ago it was conquered by the mad dictator Xemu who also plotted to invade the Earth. In order to keep his invasion plans a secret, he had agents discourage a housing development in the swamp region where the dimensional pathway existed. These strange happenings attracted the attention Mr. Fantastic of the Fantastic Four who sent the Human Torch to the location to investigate. The Torch was captured by Xemu's men and brought to the Fifth Dimension, where he assisted the locals in liberating their world and overthrowing Xemu before the Torch returned to his own dimension. 
Years later, the 5th Dimension was manipulated along with other worlds by Arkon of the planet Polemachus in the Earth dimension. Using a phony company called Inter-Politan Thermo-Dynamics Unlimited, he sold weapons to the people of the Fifth Dimension to defend them from an apparent invasion from Earth-721 in a wider scheme to cause nuclear wars on Earth-616, the Fifth Dimension and Earth-721, thus creating the power needed to renew the dissipating radiation ring around his planet. This plot was thwarted by the Fantastic Four with the aid of Earth-721's Thing. 
- No special notes.
- No trivia.
- Appearances of Fifth Dimension
- Minor Appearances of Fifth Dimension
- Media Fifth Dimension was Mentioned in
- Location Gallery: Fifth Dimension
- Images related to Fifth Dimension
- Marvel Staff members who were born in Fifth Dimension