As I’ve written before, second stringers such as John Stewart and Green Arrow can sometimes make it into the A-list, as much by blind chance as innate quality. Dr. Light shows the reverse is true: once a minor A-list villain at DC, he became first a joke, then a monster.
Dr. Light impressed me with his first appearance (cover art by Murphy Anderson, all rights with current holder) for his super-villainous pragmatism: rather than steal stuff, then deal with the Justice League when they come after him, he launches a pre-emptive strike, banishing them to parallel worlds designed to neutralize their powers. Only with them gone does he kick off his plans for world conquest.
His plan did not, of course, work, so in his next appearance he takes another novel step. Rather than go after the League again, he decides to take out the individual members, one at a time. Seriously, this was a rare bit of logical thinking back in the Silver Age. His first victim was new member the Atom (as Pat’s Silver Age Comics notes, Atom covers favored death traps tailored to his small size). He followed that with taking on Green Lantern, Flash, Superman, then the Teen Titans, none of it with much success (he also did end up taking on the whole team a couple of times). Still, if not a great super-villain, he was someone you could count on for a solid scheme and a readable story (cover by Gil Kane, rights with current holder)
But then Marv Wolfman did his terrific reboot of the Teen Titans, and brought in Dr. Light as leader of a recurring adversary team, the Fearsome Five. A short-lived leader: he proves incompetent as a leader and his own team soon write him off and kick him out. I have no idea whether Wolfman genuinely thought Light was a dork or if he simply needed a buffoon villain and pulled Dr. Light’s name out of a hat, so to speak.
Either way, it was the beginning of a downward spiral. With subsequent appearances, Dr. Light become increasingly inept, increasingly cowardly, totally unable to beat anyone (the children of the Golden Age team the Blue Boys kick his butt in one story).
And then came Identity Crisis, which explained his decline as the result of Zatanna trying to mind-control him. With the mind-spell broken in the course of the story, he regained his old forcefulness … but of course, instead of Dr. Light the boob, he was Dr. Light, the rapist thug, which makes him even more unpalatable.
The New 52 reboot introduced a new Dr. Light in the Justice League of America, a good guy who gets zapped by an out-of-control Superman during the Trinity War. I have no idea where he went from there but he had nowhere to go but up.