From Wikipedia: Alignment (Dungeons & Dragons):

In the Dungeons & Dragons (D&D) fantasy role-playing game, alignment is a categorization of the ethical and moral perspective of player characters, non-player characters, and creatures.

Most versions of the game feature a system in which players make two choices for characters. One is the character's views on "law" versus "chaos", the other on "good" versus "evil". The two axes allow for nine alignments in combination.
 

Options: Lawful Good; Neutral Good; Chaotic Good; Lawful Neutral; True Neutral; Chaotic Neutral; Lawful Evil; Neutral Evil; Chaotic Evil