The Fallen was once one of the Original Thirteen - the first Cybertronians ever made. As such, he is a multiversal being and can be considered a demigod. The difference between the Fallen and his brothers is that the Fallen turned against his Creator, Primus, and went to serve Unicron, the Planet Eater.
In one dimension he was one of seven Primes who landed on prehistoric Earth, planning to destroy Earth's sun to harvest energy. There he gained his name from turning against his six brothers when he wanted to go ahead and harvest the sun in spite of the planet having sentient beings on it.
Most other dimensions, he's the one who is on fire, though he's not the one screaming - usually his enemies and victims are though.
The Fallen is the property of Hasbro and Dreamworks. I am currently playing with him and gain nothing but amusement doing so.