First two pics are the hot candidates for the role of gnoll chief.
That "Razorpaw" guy looks absolutely great, but he would also look completely different from the other gnolls, almost like a rat-man.
Where is the original pic from? Does he appear in other UA mods?
The last two pics are two more random gnolls.
I think I'll take up the duty to compile a gnoll pack (tentatively named "gnoll call"), as soon as I find the time.