Eric O'Grady is a low-level Irish agent of
S.H.I.E.L.D. who stumbles upon
Dr. Henry "Hank" Pym's latest incarnation of the Ant-Man suit in the S.H.I.E.L.D. headquarters. A man of very few morals with a willingness to lie, cheat, steal and manipulate in order to get ahead in life, O'Grady immediately steals the Ant-Man suit for his own selfish plans, which include using his status as a "super-hero" to stalk women and facilitate his thievery. A running theme with the character is his evil side clashing with a desire to be accepted by others, which leads to O'Grady vowing to renounce his evil ways and become a proper hero, causing a cycle of the character relapsing and vowing to "change". When
Wolverine attacks the S.H.I.E.L.D.
Helicarrier,
Mitchell Carson orders O'Grady and his roommate Chris McCarthy to guard
Hank Pym and the new Ant-Man suit. Pym walks out and they panic and knock Pym out. McCarthy accidentally runs off with the suit to escape Wolverine, Instead of returning the suit, he uses it to steal stuff and spy on the women's showers. When O'Grady joins fellow S.H.I.E.L.D. agent Veronica King, McCarthy's girlfriend in mourning his death, they start a brief relationship with Veronica getting pregnant. Carson, originally trained to be the stolen Ant-Man suit's wearer, was forced to wear a hastily built prototype suit and track down the thief. In the ensuing battle, O'Grady disfigured Carson's face by accident with his suit's jets, burning the left half of Carson's face and leaving him deaf and blind on that side. O'Grady took Carson to a nearby infirmary but Carson still vowed revenge. After escaping the Helicarrier, O'Grady then uses his powers to continue peeping and only saves attractive woman who he then tries to bed. He eventually tries to sneak into
Ms. Marvel's purse. During a battle, O'Grady tries looting a jewelry store and encounters the thief
Black Fox who steals his bag of jewels. He reluctantly saves a girl's life from rubble and encounters
Damage Control's new "Search and Rescue" team. After he obtains a fake ID under the name
Derek Sullivan and comes up with the new superhero name
Slaying Mantis, this organization offers him a job and he consents. He meets Abigail and they start dating. He leases an apartment under his new name, and with Damage Control's help, begins to establish a new identity while continuing to hide from S.H.I.E.L.D. However, as Abigail begins to fall in love with O'Grady, she reveals to him that she is a
single mother with a son. This in turn triggers O'Grady dumping Abigail over keeping her son's existence a secret from him while pursuing a romantic relationship with him. Black Fox later shows up looking for the jewels. O'Grady, however, had already sold them to a pawn shop. The two work together, getting the $150,000 back and splitting the proceeds, with O'Grady keeping 15 percent. They form a close friendship afterward. During a later confrontation with Abigail, she reveals that she possesses the power to read people's emotions telepathically. She promptly states that her power reveals that O'Grady truly loves her. Before he can answer, the
Hulk begins an
attack on Manhattan. O'Grady reluctantly joins the fray by attacking Hulk from the inside of his body. However, the Hulk's stomach and innards proved to be just as tough and O'Grady ended up being discharged through Hulk's nostrils. He awakes in a S.H.I.E.L.D. infirmary, with Mitch Carson standing by his bed, stating that he is under arrest. Carson takes O'Grady to a secret room aboard the Helicarrier, and proceeds to torture him. While doing so, Carson reveals shocking secrets to O'Grady regarding his own sociopathic nature and abusing being a S.H.I.E.L.D. agent to cover up murders over the years. Just as Carson is on the verge of burning O'Grady's face with the Ant-Man suit's jet boosters,
Iron Man arrives and subdues Carson. O'Grady uses Carson's confessions of past misdeeds to frame his captor for the stolen Ant-Man suit fiasco, saying that he was only trying to stop the Ant-Man suit for being used for evil. Iron Man refuses to believe O'Grady, though Iron Man is quickly sidetracked by the arrival of the Black Fox (now friends with O'Grady after their first encounter). Black Fox demands that O'Grady be released and claims to have placed explosives on the Helicarrier in order to extort his friend's freedom. O'Grady refuses Black Fox's claims to protect him from Iron Man, leading to Black Fox being arrested. Several weeks pass and it is shown that O'Grady has resumed his post upon the Helicarrier, having been offered his own job under unknown circumstances. O'Grady also has one last meeting with Abigail and tells her that he does, indeed, love her. However, he tells Abigail that he will be leaving for a while and wishes to be with her. While doing so, he hopes that he can be a better person. Before leaving, he tells her his real name. In particular, during his first meeting with
Taskmaster, O'Grady attempts to slander the Ant-Man name of his predecessor
Scott Lang by passing off stories of his lewd stalker behavior regarding Ms. Marvel onto Lang, as well as claiming that Lang was never an official member of the
Avengers. When
Stature overhears Taskmaster and O'Grady laughing at these lies, Stature attacks by growing to giant size and attempts to step on O'Grady. As Stature and O'Grady's fight begins to attract the attention of people outside the Initiative compound, Taskmaster brings them down with his shield. O'Grady discovers the Skrulls' last resort plan: to open a giant
Negative Zone portal, and have the entire United States removed from this dimension. Escaping the Skrulls on the back of one of their shock troopers, O'Grady brings the information to some of the remaining Initiative members, and they set out to stop the plan from happening. Following the Skrulls' defeat, O'Grady is commended for his good work, and is promoted to a position in the
Thunderbolts during the "
Dark Reign" storyline. However, O'Grady began to regret his actions in the Thunderbolts but can not do anything since Osborn would have him killed.
Paladin advised that he wait until Osborn
inevitably goes insane and is taken down. Ant-Man later secretly witnesses Paladin,
Ghost and
Headsman turn against
Mister X and
Scourge when they are ordered to execute the original
Black Widow and
Songbird, then erase their teammates' memories. He later assists in the capture of
Luke Cage by entering Cage's nervous system. However, when his teammates make no effort to extract him, O'Grady helps Cage to escape. O'Grady becomes increasingly disgruntled with the Thunderbolts, and concerned for his future. In order to earn some goodwill, he helps
Captain America escape from custody, asking that he keep this in mind in the future. Later, when sent with the rest of the team to infiltrate
Asgard and steal
Gungnir, he once again faces off with Stature. After Scourge finds Gungnir, he attempts to take it to the Iron Patriot, but is stopped by Paladin finally having enough of serving a madman.
Grizzly attacks Paladin to kill him for treason but O'Grady shrinks down and enters Grizzly's ear canal, incapacitating Grizzly and saving Paladin's life. As the
Mighty Avengers defeat what remains of the Thunderbolts, O'Grady finds Gungnir and gives it to Paladin, who hides it from the Iron Patriot. After the battle, O'Grady decides to re-evaluate the choices he has made and to do something good with his life. Eric O'Grady is later seen as a member of the
Secret Avengers, using the real Pym's classic Ant-Man gear. O'Grady is positioned as the rookie of the group and is teamed up with
War Machine, who believes O'Grady is not worthy of the Ant-Man name. O'Grady uses his position with the Secret Avengers as a tool for sexual encounters with various women.
Black Fox comes to him with info regarding
A.I.M. to hopefully boost O'Grady's relationship with Hank Pym. When Abigail comes by, O'Grady admits his longing for a relationship with the intention of starting one, only for Abigail to find evidence of him being unfaithful. After running into
Striker,
Finesse and
Veil, O'Grady talks the ladies into a private drinking party, where he passes out and they put shaving cream on his face before leaving him. After waking up, O'Grady is faced with Striker, who he blames for the shaving cream incident and starts a fight with. Tigra saves O'Grady from Striker as Pym explains the situation. On a mission against Father (the creator of the World facility) with the Secret Avengers, O'Grady is beaten to death by Father's henchmen while defending a child's life. It is later revealed that Father created a Life Model Decoy of him (with all of his memories and returned to a amoral mindset) to replace him, who later becomes the supervillain
Black Ant. ==Powers and abilities==