How can Marvel use Fu Manchu if the licensing deal is expired, even if they don't name him?
As you well know, the copyrights on characters have an expiration date and the original Fu Manchu novels have been in the public domain for a number of years. That means that anyone can use those stories without issue. So Marvel can use Fu Manchu as a character in their stories.
Wait, but if the stories are public domain, then why the name changes?
While the stories themselves have entered the public domain a long time ago, the Sax Rohmer estate has received a TRADEMARK on the name "Fu Manchu." Thus, Marvel would not be able to use the name on covers or any kind of advertising and, to be frank, such limitations are more trouble than they are worth. For instance, DC has been able to call their hero "Captain Marvel" within the comics for years while Marvel held the trademark on "Captain Marvel," but eventually DC got sick of that and just decided to re-name the character Shazam. It's a similar deal here - if you plan on using a character in stories, you want to be able to promote the character or use their names on book covers, ya know?
So why can't they collect the stories and just not use Fu Manchu's name on the cover?
This is likely more a situation of the particulars of the original licensing deal than anything else. If you have a licensing deal with someone, it typically includes provisions as to how the work can be reprinted later on. This is why IDW and Dark Horse were able to reprint G.I. Joe and Star Wars comics that Marvel originally produced after those two companies licensed the rights to G.I. Joe and Star Wars, respectively.
However, Marvel managed to cut a deal with the Rohmer estate and they approved a four-omnibi collection of the entire Master of Kung Fun series a couple of years ago...
I imagine that the Rohmer estate is reasonable enough. They know there isn't exactly some huge demand for comic book adaptations of Fu Manchu, so they worked out a deal to get some money rather than no money.
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