While NoMachine can integrate seamlessly in any of the supported environments, the 'nx' and 'NX' names are reserved and cannot be used on the system for different purposes than NoMachine itself.

NoMachine creates on the system the 'nx' account used for internal handling of the program's operation and creating a separation layer between the other system accounts and the nx account. The nx account, which is also a hidden account, cannot be used by users (privileged or not) to log-in directly to the system (e.g. via the login Window or via a SSH client that is not NoMachine). Admin privileges cannot be removed from user nx, neither the nx account cannot be deleted from the system or the NoMachine server will be no longer operational. Having another 'nx' account on the system, not generated by NoMachine, will result in conflicts.

In a similar way, also the 'NX' is a reserved name that cannot be used as hostname.

Please do not use 'Nx' and 'nX' as well.
 

NoMachine server (except the free version) creates on the Linux and macOS system also the 'nxhtd' account 
which is the user of the built-in web server, nxhtd. It has the same level of permissions of the Apache user, for example www-data. On Windows, NoMachine server doesn't create the nxhtd user because the web server (nxhtd) works as system service.