This is Machai in his feral form. He's an adult scimitar-toothed cat in his prime. I will expand this further once he has a backstory.
Notes: For those drawing this character, the body spot pattern is not necessarily set in stone; however, I'd like the facial stripes to be distinct and recognizable.
General species references (not by me) can be found on DeviantArt:
http://www.deviantart.com/browse/all/?section=&global=1&q=machairodus
http://felinefire.deviantart.com/art/Machairodus-and-Megantereon-582862223
(Considering this creature is now extinct, its fur volume and patterns are open to interpretation.)
Some skull refs:
http://bloximages.chicago2.vip.townnews.com/dailytimes.com/content/tncms/assets/v3/editorial/f/9c/f9cffb24-d6cf-11e1-a7fd-001a4bcf887a/5010b6058d4fa.image.jpg
https://boneclones.com/product/sabertooth-cat-chinese-machairodus-giganteus-skull-BC-102 (actually an m. giganteus, for lack of something better)