Mason and antiquarian book collector here.

While conspiracy theories have been around for as long as their targets have, the revival of the "world domination" conspiracy comes with Nesta Webster's 1921 book, Secret Societies and Subversive Movements.

It's not necessarily that she invented much in terms of new content- there already existed anti-Semitism, accusations of subversive political movements, conspiracies regarding the banking industry, and accusations that Adam Weishaupt's Bavarian Illuminati hadn't been the failure that we know it was after it was banned by Karl Theodore of Bavaria.

Her claim to fame was taking the above and attaching them all together, forming the modern (post 1920s) "international Masonic Zionist banker conspiracy" that we find today on poorly-formatted conspiracy nut websites with bright flashing graphics.

As a collector of Masonic books, I couldn't resist picking up a copy of Secret Societies and Subversive Movements when a first edition was offered to me from a book dealer I know- it still gives me a good laugh when I look over at my bookshelf.

If you're interested in reading this text for yourself, Project Gutenberg has the text here.