I was sitting here thinking about some games where you can make characters and such and I wanted to know what games (excluding multiplayer) has a pretty good create a player feature. Any game on any system.
Dragon Quest IX: Sentinels of the Starry Skies
Phantasy Star 0
Animal Crossing: Wild World
Animal Crossing: City Folk
The Elder Scrolls III: Morrowind
The Elder Scrolls IV: Oblivion
The Sims 2
The Sims 3
URU: Ages Beyond Myst
Dragon Age: Origins
3D Dot Game Heroes
The Dark Spire
Etrian Odyssey II: Heroes of Lagaard
Etrian Odyssey III: The Drowned City
Definitely Spore. How you create your character affects the game. Although, this gets less important as you progress through the game. The only "multiplayer" feature is that the game downloads other user-created content that appears in your game.
Demon's Souls had a pretty kick ass character design system. In terms of character appearance probably the best i've seen so far, and in terms of how you wanted the character to work in game, it was pretty comprehensive. They tended to get a bit samey once you reached the higher levels though.