[tesseract]

You could trademark it and then license the trademark to companies that you want to allow to use it. This is pretty common. Some reasons I can think of for this kind of arrangement:

* Parent companies licensing their trademarks to subsidiaries.

* Unrelated companies using similar names who enter into an arrangement where one owns the trademark and the other licenses it. E.g. Tyco International/Tyco Toys, ITT Corp/ITT Tech, Apple Inc/Apple Corps (after Feb 2007).

* Certification, compatibility, or similar logos can be trademarked and licensed to authorized users so the owner can protect against the logo being used in an unauthorized or misleading fashion. E.g. UL Listed logo, Orthodox Union kosher symbol, Windows compatibility stickers.

* Franchising and similar situations. E.g. car dealers, fast-food restaurants, co-ops like IGA and Ace Hardware.

* Avoiding legal hassles that might ensue if the name/logo were not trademarked. E.g. Linux.

[kwamenum86]

Images are copyrightable. It would never make sense to trademark an image because if you can put the image in a fixed medium a) it is free and b) it is protected much longer.

[tesseract]

Copyright only lasts for a certain number of years (unless you're one of the people who thinks the government is going to extend copyright terms forever so Micky Mouse never falls into the PD...) whereas trademarks last forever if you can enforce them.