I once saw it on the late late show on a UHF station, after “Creature Feature.” It involves an innocent young yokel who comes to the big city and somehow gets caught up in a crime – a femme fatal named “Plethora” plays a role, IIRC – gets killed, and then is resurrected as a supercool superhero by a mad scientist and goes out for justice/revenge. The script belabors the ethics of vigilantism – the hero, having killed a couple guys, defends himself, referring to the scientist – “To fight for good you must destroy evil! He said it himself!”
Just so you know, you can search IMDb by character name. That brings up Fearless Frank as the only exact match for the name “Plethora.”
That’s how I did it. After that it was a quick Google search that brought up this summary, which seemed to closely match BrainGlutton’s memory.
Believe it or not, I was actually thinking about FEARLESS FRANK a few days ago in the context of “Movies that were on TV all the time when I was a kid that I haven’t seen in years”… that really needs to be on DVD.