I have been developing a story for some months based upon a fictional character that i thought I had invented uniquely ... let's say a half zebra half elephant for example. I named it elezebra. I then find a book written about ten years ago with the same name and character.... I don't think it sold much and I certainly had never heard of it before ... but the name is obvious because it describes the character .... (not like Elezebrer or Eleezebra ...which might make it more unique) Unfortunately the name has been trademarked 9 years ago by the other author... I even have celebrities endorsing my facebook page for it ....(not elezebra by the way)... so I have spent a lot of time and money on my process. Will I have to change my characters name .... :-(
Yes, I believe you will have to change your character's name.
I'm not a lawyer, but I believe if the name is trademarked, you can't use it, and you probably can't use anything like it for such a similar character.
The idea of combining these two species is not copyrighted; but a trademark is different than a copyright: A jury can decide anything similar to the trademarked symbol, word or phrase is a violation, you trying to cash in on the fame of the existing work. Even if that is untrue (nearly everybody denies it, just denying it, even under oath, is not a convincing argument.) It is their judgment call, even if they do believe you: If the names are too similar, you are in violation of trademark and liable for damages, end of story. You cannot profit using that name.
Bite the bullet and change the name to something that nobody will think is remotely close to "elezebra".