A worker at a Pittsburgh steel mill once visited by Thor[1], Joseph Conroy found a flake of the Thunder God's magical uru hammer, incorporating it into a good luck charm keychain. Damaged battling the Destroyer, this fragment of Mjolnir was accidentally left behind when the mortal forges were appropriated in its repair.

Falling under Maggia control a few years later, Conroy threatened to expose the mill's crooked puppet boss, Mr.Paretta, to the police. Paretta ordered another employee to push Conroy into a vat of electrified, white-hot liquid metal. Originally thought incinerated, Conroy's ever-present uru chip instead mutated him into a superhumanly strong creature composed of flaming molten "living slag", capable of radiating intense heat and draining energy from available sources.

Avengers Wonder Man and Iron Man, coincidentally visiting the facility on a Stark business venture, oppose "Inferno" but he defeats them, single-mindly chasing Paretta through Pittsburgh as more Avengers are called in. Finally cornering his old boss, Paretta confesses his wrongdoings. Having overheard, Captain America promises the criminal industrialist will see justice. Satisfied, Conroy walks into a nearby river, seemingly dissipating himself[2].

Resurrected some time later as part of the Grim Reaper's Legion of the Unliving against the Avengers[3], Inferno attacks Crystal. However, before he could kill her, the Reaper loses control of his undead pawns as the entire Legion is drawn into a dimensional vortex by demonic entity Lloigoroth[4].


Conroy was altered by exposure to molten steel and a flake of Thor's enchanted mallet Mjolnir. Conroy became a huge creature of molten steel & slag, and radiated great heat at all times as a result. He could increase the amount of heat he radiated at will, and could project molten steel from his body. Inferno possessed great superhuman strength, at least class 50, and possibly reaching class 100, and was sufficiently durable to withstand several blows from Wonder-Man with ease, although at times he also appeared semi liquid and could allow bullets to partially pass through him (and presumably melt!). Due to the Uru flake embedded within Inferno's right palm he was also endowed with Mjolnir's energy re-directing properties and could also absorb and re-direct electrical energy such as he did with Iron Man's armour.


Could sense whereabouts of Vince Paretta & Tim Turpin

Strength level

At least superhuman Class 50 (possibly class 100)


Mute in Inferno form, and also possibly suffered from reduced decision making processes, acting more out of pure vengeance than any obvious cognitive mental faculties.







Joseph Conroy's mutation was heavily implied to be due solely to the flake of Uru from Mjolnir that he carried as a good luck charm key-ring which after the attempt at killing him became part of his right palm.

In Conroy's first appearance in Journey into Mystery # 120 when he met Thor, his character was not specifically named.

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