Wiki: "1977-: Advanced D&D
Stephen R Marsh claimed that when Gary Gygax was developing
Advanced Dungeons & Dragons, he convinced Gygax to add a Good and Evil axis to D&D's character alignment system. (Originally, characters could only be Lawful, Chaotic or Neutral. By adding a second axis, the number of possible alignments based on combinations of Law, Chaos, Good, Evil and Neutral grew from three to nine.)"
- producer Vincent Florio (2011-09-05). "Interview with Steve Marsh". Save or Die. 14:00 minutes in.