Similar to this question for information on how to root different devices, should a community wiki exist for whether the bootloader can be unlocked on different devices and how this is achieved?
Just thought it may gather information in one place.
We can deal with that as with How do I root my Android device?:
As with the rooting question, the (only) answer should contain nothing but links to the corresponding questions, and one such question allowed per device. Exceptions might be considered when a newer Android version requires a different approach.
PS: We should link to that question then from our bootloader tag-wiki, to make it easy to find.