If the game is not set in my over-arching campaign setting (such as when I ran WLD), then you can play whatever you want. Half-vampire wookie barbarian? Sure.
If the game is set in my over-arching campaign setting, however, you can consult the campaign Player's Guide as to what races/classes are allowed. If you include sub-types (such as human racial groups), this means that you have a much wider range of choices than the Core Rules allow (my campaign allows characters such as a Chimpanzee Ranger, giants, half-bugbears, and humans ranging from the psychic and technologically adept Indrus to the barbaric and gruff Bearfolk). I have largely re-written the classes, in part to lower the magic level of the world, and in part to introduce a skill-based combat system.
Every 5 levels, a character gains a "legacy". Character legacies can be used to (among other things) introduce new feats, spells, and prestige classes.
There is a huge range of options in this system (IMHO), with characters who can be humanoids, fey (elves, gnomes, faerie animals [western hengeyokai]), magical beasts, or giants (including dwarves). There are lots of class options. If you cannot find something you want to play, and believe that the system is too restrictive, I am happy to direct you to other games that are less restrictive.
RC