Nope, you can't.
Also, yay, someone who recognizes the game and plays DF! Dwarf fighters are actually really quite powerful, if you get some decent gear. So, kobold wizard... likely a poor idea, but that's ok. I like kobolds.
Edit: Still counting more votes.
Double edit: Vampire necromancer and troll monk.. both quite powerful. The fourth place on my scoreboards (though, admittedly, fourth place by a mile) is occupied by a troll monk. Third is an orc Makhleb Chaos Knight, second a mountain dwarf fighter, and the first a hill orc priest >_>