The character that Gavin Hammond voiced in Batman Begins first appeared where? 
Batman Begins (video game):  The film's original cast provided a voice-over reprisal in the game, with the exception of Gary Oldman, who portrays James Gordon, replaced by Gavin Hammon. James Gordon (comics):  The character debuted in the first panel of "Detective Comics" #27 (May 1939), Batman's first appearance, where he is referred to simply as Commissioner Gordon.
"Detective Comics" #27