I remember Grievous with yellow, more serpentine, pupils; the rest is pretty close.
Ok, crap, it needs 100+ words. Your style is expressed great in this one, as always. You're missing where those "marks" (three on the left and on the right) on the sides of his head are actually part of uplifted grooves. I found a great reference picture that might help you add some more detail; like the part that joins to his mouth below the 'rivets' there.
The form, and proportion are great. All in all, I think you just need to study the image a little and add a few small details; and definitely (in my opinion) put in the "snake eyes".
They were intentionally white. I didn't think to make them yellow. The pic I was using for reference, and the look I was going for, was the Clone Wars Grievous. His eyes in the pic were serpentine, but a bit washed out, so I didn't think to really make them yellow. Glad you like him despite it!
Looks awesome! But his eyes aren't yellow, and he's missing the grooves right above his eye holes. Unless that was intentional...but it's still pretty cool! I especially loved the "cough, cough" bit at the bottom. Nice touch! Can't wait to see the next one!
I know how that goes. I know backgrounds adds alot to the final art, but by skipping it, I'm able to put out more characters on a steady basis! (Thou Chad Fuller still gives me hell on a regular basis for not doing background art! LOL!)