It is not an exaggeration in my mind to say Denny O'Neil is one of the single most important figures in US Comics history. He may not have had the visibility of Julius Schwartz, Stan Lee, Frank Miller, John Byrne, Alan Moore, Neal Adams and the like but it is both his written output, the books he wrote for, and the more subtle behind-the-scenes work he did as editor that made an indelible impact at both DC and Marvel Comics.
His Batman run with Neal Adams. His later steering of the character as editor in the late 1980s and 1990s.
Redefining Wonder Woman in the early 1970s
Redefining (or attempting to) Superman at around the same time
John Byrne's Alpha Flight
Redefining Vic Sage as The Question
Green Lantern & Green Arrow
A memorable run on Iron Man with Luke McDonnell
His underappreciated run on Daredevil with the Micah Synn storyline among others is a personal favourite of mine.
Looking at his other work, of which I was unfamiliar with(!) Sees him working on the X-men! Reviving Captain Marvel, GI Joe, the Justice League, Spider-man and even Pulp hero The Shadow.
He did everything. Like so many readers of comics growing up I realise that he is a figure who helped directly shape my entire love and enjoyment of the medium growing up. He wasn't a celebrity creator, but his mark on the output of DC and Marvel speaks for itself - outstanding and very often groundbreaking.
Thank-You so much Denny O'Neil.
Wasn't he the One that tried to make Supernman power levels more realistic during the PC days, as he had the sandman Supes drain away like 1/3 of his power?