Legendary artist. Arguably the best of all time. His comics are some of the most highly collectible and sought after. He has done work in the past that helped to revitalize characters Batman, Green Lantern, Green Arrow, Deadman and the X-Men. He dealt with topics and issues that were very controversial but made characters Green Lantern and Green Arrow more relevant.
The co-creator, alongside Dennis O' Neil, of Ra's al Ghul. Ra's al Ghul in arabic means "The demon's head." He also co-created the League of Shadows (aka League of Assasins) but not Talia al Ghul (created by Bob Brown, O'Neil and Giordano), the love interest of Batman and daughter of Ra's.
In 1970 he also famously co-created Man Bat (aka Dr. Robert Kirkland "Kirk" Langstrom) alongside writer and artist Frank Robbins in Detective Comics #400.
In Green Lantern #87 in 1972 he co-created the Green Lantern known as John Stewart alongside Dennis O' Neil (Denny). Appa Ali Apsa, Bork, Brainchild, Sise-Neg, Gaza, Merlyn and Piper are just a handful of others he helped to create.
Neal Adams is a huge creator-rights advocate and he was instrumental (along with Jerry Robinson) in the support of both Superman creators, Joe Shuster and Jerry Siegel earning recognition and a lifetime stipends from DC comics.
Back in the 1960s many creators were scared DC would fire them if they worked for Marvel as well and Neal Adams was the first artist that was not scared of this and used his name at both companies when he was doing X-Men and Deadman at the same time. Examples of artist having to uses pseudonyms would be Gil Kane had to pretend to be “Scott Edward” and Mike Esposito was “Mickey Demeo.
Neal Adams is also a key figure in the now common practice that artist keep their originals. Before Neal Adams' bold move to free held Jack Kirby art, Marvel believed they owned the originals. Some times originals were distorted, given away or just locked up. All that changed in the late 80s.
Characters Created by Neal Adams