First, a bit of background: In #17 of the classic Transformers comic (1985 or maybe 1986), we meet the Decepticon dictator who has ruled Cybertron since Megatron left (or, as it's later retconned, since Scorponok left a little while after Megatron). He's named Lord Straxxus. He dies in his second issue, but is awesome. But he's never a figure. Until 2010, when they release a figure that's clearly Straxxus, but is called "Darkmount," after Straxxus' castle in the comic.
No one's been able to figure out why. Actionfigs.com asked about it a few weeks ago in the Q&A, and here's the exchange:
ActionFigs.com: We've seen an upcoming Transformers Generations figure who is called Darkmount. He's clearly based on the Decepticon dictator from the Marvel Comics series, Lord Straxus, but the figure takes his name from Straxus's castle. Apparently, the figure is not being called simply 'Straxus' due to - as best as we can figure out - a somewhat obscure character from a Doctor Who radio drama that shares the name. However, in the past, you've often added words to copyright-issue names like 'Autobot Jazz' or GI Joe's 'Sgt. Rock n Roll.' Why did you opt to call this character 'Darkmount,' rather than using a modifier such as 'Lord Straxus' (which actually appears in his comic appearance) or even 'Decepticon Straxus'?
Hasbro: You are correct that Darkmount will soon be released at retail and by the time this answer hits the boards, he will probably already be available! To clear the air on his name, you are correct that Darkmount is in fact Straxus. While we had plans to use Straxus we were not able to clear it through our legal trademark process. So, we decided to stay as true to the character as possible and made him "Darkmount" after his castle. We knew that the die-hard fans of Transformers would get this nod!