It's a Cheetah, yellow cat with spots (tusks as well if you're tauren, I don't think NE get them). Rather ugly cheetah (/cry)
+40% speed, insta cast (but takes time to get to full speed), roughly 5% mp pool mana cost, can only use basic attack with hand held weapon, breaks snares / slows, immune to ploy, gained at lvl 30 for a few copper.