Virtually nothing is known about Zodiac's origins, other than long before the Secret Invasion, he wished to fight against the government and the Avengers having infiltrated Avengers Tower before. Underneath his mask, Zodiac appears to be just a normal person.
Zodiac was created by Joe Casey and Nathan Fox and first appeared in Zodiac #1, released in 2009 under the Dark Reign banner. He was very loosely based on concepts created by Roy Thomas for the Zodiac gang who first appeared in Avengers #72 in 1970.
Zodiac is an anarchist with dreams of one day dominating the criminal underworld. The character's debut took place when Norman Osborn pretty much ruled over America with his Dark Avengers. The character's motivation was at the time seen as rebelling against Osborn for making crime somewhat legitimate. Afterwards, the character has only made infrequent appearances where he is plotting zany and diabolical schemes to undermine those in power; namely Steve Rogers and his Heroic Age.
Major Story Arcs
A man hangs tied-up upside down, beat, and tortured. The man is then kicked in the face by Zodiac. He tells the man that he's the last one. He talks to the man and knows that he's wondering what Zodiac is doing. Zodiac then stabs the man in the gut with a knife and tells him that he learned his lesson, the hard way. The man's about to die and Zodiac tells him that he's proud that he hasn't given up any information yet. However, he said this was not an interrogation and he doesn't care about any information. He says that it's an announcement. Zodiac is then seen in a room with hundreds of dead people also bloody and hanging upside down. Zodiac draws a smile on his black mask with the blood of his victim. And to him, this is all a decent start.
Zodiac then gets a call from a man named Manslaughter Marsdale. And he tells him that the job was done with a clean sweep. It then flashes back two weeks before the incident. A man dressed in a clown costume is seen watching the television. Norman Osborn is seen on the television talking about the progress that has been made so far with him as the director of H.A.M.M.E.R. Suddenly, someone knocks on the clown's door. He cocks his gun and invites the person in his apartment. A lady, filled with tattoos, walks in and has information on the Clown. Then, Zodiac comes from behind and says not to mind the lady. He asks the clown if he's the guy who has supposedly seen it all. And he asks if it would ever come to this. To Norman Osborn leading the security and posing as the Iron Patriot. Zodiac says that he's offended by Norman as one minute, he's the Green Goblin, and the next minute, he's some superhero spending the money of the government. Zodiac's displeased by the fact that Norman wants all the villains to simply fall in line and follow Norman as he runs the whole thing and he says that isn't how Zodiac rolls. He says that he's not going to hide who or what he is. The clown asked if by Zodiac, he meant the team of bad guys based on astrological signs. The clown then asks Zodiac what was in the bag he was carrying along with him. He said that he was glad that he asked and he opened the bag. He says that there was a group called Zodiac before but he like the way it sounded and he wanted the name to be his. So Zodiac said that he made sure that the name was free for him to use and when the bag opened, heads of the members of the Zodiac team fell out. Zodiac tells him that he once had a vision of a world where anarchy was the way of life. Where being a villain actually meant something. And he realized that they already were living in that kind of world. Zodiac then invites the clown to really join the circus and follow him.
H.A.M.M.E.R. forensic agents head to the crime scene and to do a report. They discover that one hundred agents were tortured and killed by Zodiac. It then flashes back to two days before the killing of a hundred, back in Zodiac's "headquarters", the clown and Manslaughter Marsdale talk about when they were both in the business of crime. Back in present day, Zodiac hacks a computer in an old S.H.I.E.L.D. headquarters for one of his schemes. In the Baxter Building, Johnny Storm comes home with two girls. He shows them around Reed's lab when they get a security alert coming from S.H.I.E.L.D. The Human Torch then sets off to the headquarters to check it out. Johnny gets attacked by Zodiac dressed in a suit to protect him from the flames. He gets some hits on the Torch and decides to retreat. He runs through an energy siphon system and starts to taunt Johnny. Johnny flies toward Zodiac but Zodiac activates the system and Johnny is left bloody on the floor. Zodiac removes his mask and says that the rest of the Fantastic Four is next.
Johnny rests in a public hospital with Clint Barton, Sue and Hank Pym. They analyze and talk about who could have beaten Johnny down to a coma so badly. Meanwhile, Zodiac and Death Reaper hook up and have some action of their own. Zodiac presses a button and sets off a bomb. The bomb was located in the public hospital and destroys it completely. Sue gets to put up a force field in time to save her and the rest of the heroes. Special Agent Murphy, worker of H.A.M.M.E.R., goes to the site of the hospital to file a report and send it to Norman. H.A.M.M.E.R. security picks up a signal of a cosmic threat that was approaching. That threat was the planet eater, Galactus. They tell all agents and the Avengers to prepare to defend their planet in this time of need. Zodiac meets with his team and discusses their plans on taking Norman down. Zodiac tell his team about the threat and that he hacked into the H.A.M.M.E.R. security system and programmed the whole scenario to play out just the way he wanted it to. He also sets off a widespread panic throughout New York by sending a giant robot to attack the city. This though, is just a bonus part to his master scheme.
Norman and he rest of H.A.M.M.E.R. discover that the warning of an attack from Galactus wasn't real. They realize that it's just a diversion and the real threat is in Manhattan, where Red Ronin is attacking and destroying the city. Norman demotes agent Murphy for not figuring anything out. He sends Ms. Marvel, Moonstone, to go and solve the problem in Manhattan. They see that no one is piloting the giant robot. While, all of this is happening, Zodiac and the rest of his team go off to finish some business and rob a bank. Norman goes to Manhattan to take care of the giant robot himself. While fighting the robot, he gets some assistance from Reed Richards and Johnny Storm. Johnny puts down the giant robot before it could cause even more damage.
Agent Murphy heads off to his new office after getting demoted. He sees Zodiac, sitting on his office chair, waiting for him. He talks to Murphy and tells him about his agenda. He tells him that he's a true villain and not one that just bows down to Norman. He knows those who work for him, and they know him and have trust in him. Zodiac tells him about how he knew about Norman's plans while heading the security. He placed seal bugs around Avengers Tower in order to spy on Norman and his meeting with the Cabal. Zodiac knew that he wouldn't be able to take down Norman with all of Norman's connections, so Zodiac went to the Ankh Dimension, which some believe doesn't exist, and he got his hands on the Zodiac Key in order to make the scales more to his favor. Agent Murphy is found dead later on in his office and Zodiac says that he's about to get it on.
After several attempts to assassinate various supervillains, it was revealed that the Young Masters of Evil's mysterious benefactor was none other than Zodiac. He promoted the last remaining Young Master, Egghead, to the role of his new foot soldier while musing of his brilliant orchestrated events as comparable to Darwin.