Within a year of MLJ launching the first comic-book crossover. they used their new feature "Steel Sterling" to debut a villain who would reform and get his own feature as a costumed hero in a scant few months.
First, in ZIP COMICS #10 (1941), Sterling battles a trio of circus-skilled thieves: strong man Hefto, rubber-man Twisto, and fire-breather Inferno. Hefto dies in that story while Twisto and Inferno escape.
In ZIP #11, Twisto and Inferno part ways. Twisto is captured by the law, but as in compensation, a new, more formidable villain takes his place: the devilish, poison-using Rattler. Sterling masquerades as a crook in order to trap Inferno, but the two of them end up battling the Rattler. Inferno gets poisoned, but after Sterling saves his life, the fire breather swears to reform. His intent to reform cancels him out as a "villain," but the story still registers as a villain-crossover thanks to the presence of both Twisto and The Rattler, while Inferno's grooming as a future hero makes his presence a proto-crossover of two heroes.
In ZIP #12 Inferno helps Sterling capture the Rattler and then surrenders to the law. However, in #13, Sterling goes under cover in prison to catch another bad guy, and once again Inferno, in the same prison, renders aid. A possible parole is mentioned by the warden.
In BLUE RIBBON #13. Inferno's still in prison, but he breaks out in order to foil the plan of other prisoners to kill the judge who sentenced them, and Inferno as well. Once the threat is neutralized, the judge suggests that Inferno (no other name is given) should remain a fugitive while taking up the superhero game. He only enjoyed six more solo adventures, but at least in the last one, it was stated that the governor has pardoned the former felon. And as far as I know that ended the character's Golden Age adventures, though he was revived in the Silver Age once to team up with The Web, and may have been revived elsewhere in other unsuccessful reboots of the MLJ line. (In the 1967 story, yet another hero, the Fox, has a non-speaking cameo.)