This is Sookaiya "Soo" Venatosh, a prominent character in my sci-fi e-book series Riesel Tales: Two Hunters. She is a Binnikod (collie/bull aliens), hailing from planet Brysance, and works as a mercenary. Her legs are robotic, the originals having been lost in a battle earlier in her life.
She's rather brash and reckless, but makes up for it with tactics, armor and firepower. She has enough attitude for a dozen people. Her larger gun can fire explosive rounds and is eight feet long, two inches taller than she is.
Drawn in pencil; colored/shaded in PS CS2.
Read more about the book here: http://rieseluniverse.com