— Himself
Background
Felix Patrick Hardy was born to Walter Hardy and his wife, in one of his... admittedly failed attempts to settle down and have a family, to forget his life as a cat burglar. This one was just like all the others, and in short order his wife left him, leaving him with the child. One might have expected Walter to just throw the kid away, put his son up for adoption... but he didn't. No, he took responsibility and raised the child himself.
Of course, this meant he raised the child in his way of thinking, and taught him to do illegal things. As a result, Felix was picking his schoolmates' pockets at the tender age of seven. Beyond that, though, Walter taught Felix a lesson he would carry throughout his life -- never settle. If he wanted something, he should never stop working towards it until he got it.
When he was in his early teens, he started noticing things going very well for him... and very badly for others who tried to cross him. Like a black cat, he just seemed like he was bad luck for people who had beef with him. He never understood what was going on, just put it down to being get well-prepared, skilled... or just better looking. Life clearly liked him more!
The lesson of never stopping his pursuit of the things he wanted would rear its ugly (or would that be beautiful?) head when Felix had grown. Walter Hardy was arrested for a robbery, but it was one that he had not committed. So Felix went to a few of his dad's old contacts, and they found evidence of Walter's innocence.
Of course that wasn't enough. The wheels of justice are slow to turn, and Felix decided he wasn't going to just wait for them to decide to let his dear old dad go. So again talking to some of Walter's old crime buddies, they decided they'd help him do one more job -- busting Walter out! This was when Felix donned a costume for the first time. Given how luck just seemed to favor him, he decided he'd call himself "Black Cat".
The jailbreak was successful, of course, and on the way out, Felix left the evidence of his father's innocence (wiped free of prints, of course) on the desk of the warden, as well as sending separate copies to every newspaper in town! It didn't take long before there was public outcry that someone who had served his time in prison was still being harassed in his older years. The courts decided to drop any charges, so that wherever Walter Hardy was, he could live free.
Of course, "Black Cat" was now on the radar...
When Walter Hardy saw how well Felix handled himself in the jailbreak, he decided he would pass on his thieving techniques to his son. Better Felix go out there fully armed with equipment and knowledge than to go bumbling around and get caught immediately. So he began to build devices for Felix to use in his burglary. And from there, the legend of "Black Cat" began to take shape!