Although I've never, to my recollection, read a comic with the original Foolkiller in it, I must admit that I found his story as related in the Official Handbook of the Marvel Universe rather intriguing; the psychologically unbalanced moralist seems like a natural for the vigilante schtick, and it's interesting to see which vigilantes get the implicit approval of the publisher (Punisher, for instance) and which do not. Also, maybe it's just my age showing, but I think he had a pretty striking costume:
It's certainly better than the outfits of the two who followed in his footsteps:
Foolkiller also got re-envisioned for the 2099 world, and the concept was revived for a Marvel MAX series. I don't know what the character concept's status is in the 616 universe.