The U-Foes are a team comprising of the four gamma mutates Vector, Vapor, X-Ray, and Ironclad. In an attempt to recreate the Bio-Tech Force Enhancement Project, these four individuals went to great lengths to copy the accident that created the Hulk. Simon Utrecht, a former politician and multi-millionaire industrialist, funded the operation in order to gain power, and gained the support of Ann Darnell, Jimmy Darnell, and Mike Steel. The group exposed themselves to dangerous levels of gamma radiation which most likely would've killed them or given them terminal illness if the project wasn't successful. The gamma mutation experiment succeeded and the group gained superhuman abilities, however, before the experiment could be properly completed the test was interrupted and Utrecht Laboratories was destroyed.
The four emerged from the wreckage of the facility as superhumans, and went on to become the group known as the U-Foes. When word got out of Utrecht's experiments, the United States Armed Forces came to his facility to arrest him and the rest of his group. A battle ensued between the military and the U-Foes, but the U-Foes lost due to their inexperience with their newly gained powers and inability to fight as a team. In the end, their own ongoing mutations incapacitated them, and the team was arrested and placed in custody as they lost control of their increasing abilities. The U-Foes were imprisoned in the Vault alongside other supercriminal inmates until a breakout occurred when SHIELD fell in 2014. The U-Foes were recruited by the Leader, and in exchange for their services, he helped stabilize the U-Foes gamma powers.