An early model of player types from the late 1970s by Glen Blacow. This divided role-players into four groups: "Roleplayers", "Storytellers", "Power Gamers", and "Wargamers". This was later adopted by Robin Laws in his book, "Robin's Laws of Good Game Mastering". Laws includes seven types, however: The Power Gamer, The Butt-Kicker, The Tactician (i.e. wargamer), The Specialist, The Method Actor (i.e. roleplayer), The Storyteller, and the Casual Gamer.

References:

• Robin's Laws of Good Gamemastering(approve sites)
• Player Types (from Glen Blacow and Robin D. Laws)