A few thoughts.
The Barbarian: The kobold himself is well done. Good animation and presence. His mace, however, is funky. It should be redone.
The last picture is a disappointment after the previous illustrations. As a whole it is rushed and clumsy. Go ahead and do a new illustration of the subject and his cat.
The impression I get is that these kobolds are medium-sized. In addition, they're too damned muscular to be real kobolds. You need to make them smaller and slimmer. In addition, kobolds really aren't known for their muscles, they tend to be wiry instead. I can understand the desire to make them more impressive, but they're really not the sort of beast one would consider a hunk.
To put it another way, there's a good reason why kobolds are known as sneaky little tricksters.
Oh heck with it...
Go ahead and redo all the classes you've done. But try for a more traditional kobold. And this time do some preliminary sketches. Multi pose studies and alternate views. Polish the final art as much as you can, and be free to trash anything that doesn't satisfy your ascetic sense.
The pictures you've already done are not a lost cause however. Create a new reptilian race to go along with them.
I look forward to more of your art.