More importantly perhaps, what do you feel is lacking from your repertoire?

For me, most obviously, is women. I don't feel like I can portray a woman effectively, despite feminist pseudo intellectual bullshit claiming a complete lack of differences between sexes there is clearly huge social disparity and some biological differences between the sexes, and I don't think I can do them justice very well. (Anna is, for the record, my first female character on RPG.)

Next up is probably straight up good guys, though I have a smattering of bad people the vast majority of my characters fall into that shade of gray region of neutrality, perhaps because they are the easiest characters to set up fights with, without being a straight up evil bastard. 

Also, the vast majority of my characters are ordinary humanoids, most even relatively human in nature, I lack Khan's fascination with beasts and monsters.