Was The Fallen ever mentioned or appeared in any of the other Transformers canons or was he made entirely up for the film Transformers 2: Revenge of The Fallen?
Looking for instances of him in any of the cartoon canons.
He was first created for the Transformers: War Within: The Dark Ages comic book mini-series published by Dreamwave, a story line that was never concluded due to Dreamwave going bankrupt.
In the Aligned continuity (War for Cybertron, Fall of Cybertron and Transformes: Prime), the Fallen was a name given to Megatronus, one of the Thirteen Primes and the first Decepticon.
Has has made no cartoon or animated appearances so far.