[@Darkmatter]
Not necessarily specific types of characters, but characters you hope to have that could easily be involved with the plot. I've often observed characters being made and then doing little with the core story simply because of its nature by design.

For example, you wouldn't want us to create a hobo just because someone thinks it would be 'fun' to play as one in this setting. It's an extreme example, but I think it illustrates my point clearly.