It is necessary sometime to have the user which will be nobody in the system but still be able to run specific process or software on your Linux system.
Usually some packages like nginx can create such users, usually called nobody. And you can use this nobody for your purpose. But if you wish to have non privilege user user with specific name, use the simple command useradd.
For instance to create user userx run the following command: useradd -s /bin/false userx.
To newly created user try id command: