Removed the bit about Graz'zt and Orcus wanting to overthrow Demogorgon in Dungeons And Dragons because they're not his minions. They're more like three rival kings who hate each other equally, and Demogorgon is just the most powerful.

Because there is so much potential for overlap and a ton of other related tropes there needs to be more focus on what makes this trope distinct from others like it, and why it shouldn't just be merged with existing subtopics. Is it a base topic that other things are subtopics of? If so, a sliding scale would be helpful.

Would you say Margaret Thatcher's government pretty much pulled a Starscream on her?

I'm not sure if this trope really needs a rename, but since many tropes on this site have gone to more universal and less character specific titles, I'd like to suggest a more generic name for this trope.

"The Usurper".

Generally, The Starscream is plotting to do exactly this, and it's basically the original's MO against Megatron, so renaming the trope to this makes it more universally understandable outside the Transformers fandom.