From Monkey Island wiki
Adam Harrington is a voice actor. He has the distinction of being the only person other than Earl Boen to have voiced LeChuck in his undead form; Harrington voiced the Demon Pirate in "Launch of the Screaming Narwhal", the first episode of Tales of Monkey Island, because Boen had entered partial retirement and was unavailable. (The lines have since been re-recorded by Boen and later releases do not feature Harrington's voice work.) Harrington also voiced Moose in "Lair of the Leviathan", the third chapter of Tales.