Un-Men are artificial creatures made from spare cadaver parts and brought to life through a collaboration of scientific and magical techniques. So far, only three scientists have been able to create Un-Men effectively.
Anton Arcane was the creator of he very first Un-Men. He first experimented with the dead bodies of Allied Soldiers when he was working for the Nazi's in World War II. His ultimate goal was to discover the secret to immortality. He instead discovered a crude manner of creating life in stitched up corpses and artificial bodies. He used his Un-Men for a combination of purposes. Some he used for further experimentation. Others, he used as servants and lab assistants in Castle Arcane. He also used his Un-Men as soldiers to attack those who crossed him. At one point, Arcane even turned his half dead brother into an Un-Man to save his life (Gregori Arcane was later known as the Patchwork Man, and encountered his brothers greatest foe, the Swamp Thing, on multiple occasions). Arcane's Un-Men have saved his life on multiple occasions. They collected his body from the mountainside of Castle Arcane after he had fallen out of his window while battling the Swamp Thing. They surgically removed his brain and placed it inside of an Un-Man body in order to keep him alive. They later dug Arcane's brain out of his Louisiana grave site and attached it to a newer Un-Man body after his second battle with the Swamp Thing. Despite their unquestioning loyalty and frequent usefulness, Arcane treated his Un-Men horrendously. He chained them up in the prison cells and basements of Castle Arcane when he found no use for them. When Arcane returned to earth in the form of a demon, he had outgrown his artificial monsters and relied solely on his hellish powers.
Doctor David Manguy was a scientist who created his own Un-Men by breading 1st generation Un-Men. He was hired by the United States government to become the team leader for a top secret operation in Louisiana, which primarily focused on "genetic exploration". Manuy was given a group of "specimens" the US government had found, which turned out to be left over 1st generation Un-Men created by Anton Arcane. David Manguy, thinking he was working on an experiment to prevent birth defects, bread the Un-Men and gave their next generation a serum, which was meant to correct any and all of their parent's genetic defects. Only one of these 2nd generation Un-Men survived, and that was the Un-Man Damian Kane. Damian looked like a normal human being, but as he aged, his body to reverted into a horrible monstrosity.
Cranius is a surviving 1st generation Un-Man created by Anton Arcane. He is a small creature that looks like a head sewn onto a hand. He was a witness to Arcane and the Swamp Thing's first two battles. However, during the second battle, undead spirits hypnotized Arcane's Un-Men, revealing to them their lonely status. The Un-Men revolted and tore Arcane's body into pieces. After this battle, Cranius disappeared for over two decades. He later resurfaced as the head and creator of UnCorp, a company run by Un-Men. He created the alias, Dr. Von Schadel and began working on new Un-Men of his own personal design, but based on the originals created by Anton Arcane. Cranius' Un-Men were much more human like, even to the point that they looked more like mythical creatures and less like horrible monsters. His favorite Un-Man creation, Neko Parish, looks like a beautiful young woman with only one arm and angel wings on her back.F
The Un-men make ther first appearance in the New-52 in Swamp Thing #10 alongside Anton Arcane who in the New 52 is the Avatar of the Rot. In this version there origin is changed from magical and scientific creations to normal humans who worshipped the Rot in life and were "blessed" with powers of the Rot in death.