[After a brisk nap]

To Kurufinwe's excellent list, I would add two guys called Chris Jones.

The first of them is the man behind Tex Murphy (along with Aaron Conners), who created the definitive FMV interactive movies and laid the groundwork for a lot of the comedy/drama games that would dominate the late nineties and turn of the century (Grim Fandango, The Longest Journey etc.).

The other Chris Jones, CJ, has never made an adventure game himself, but he created the Adventure Game Studio engine and editor, which made it much easier for non-professionals and non-programmers to make adventure games, leading to a boom in homebrew adventures. Without him, no one would probably have heard of Tierra/AGDI/Himalaya Studios, Yahtzee, Wadjet Eye Games, Gemini Rue, Ben & Dan/Zombie Cow/Size Five Games and many others.