Cover art for a made-up concept album that I've made up, entitled, "HAIL DA THANATOR!" by The Timbox Brothers (which are me, Tim, and my two brothers, Billy and Scott or so). As for the Thanator itself, it is very much James Cameron's creation.
According to his script for the movie, Avatar (2009), The Thanator "is the most fearsome of the Pandoran land predators---a black, six-limbed panther, the size of a tractor trailer, with an armored head, a venomous, striking tail, and a massive detensible, armored jaw with nine-inched fangs." It once attacks Jake Sulley in his avatar body while on his first walk in the forests of Pandora. It was later defeated by Colonel Miles Quatrich in his AMP Suit.