List all MySQL users

SELECT host, user, plugin FROM mysql.user;

Example output:

+-----------+----------------------------+-----------------------+
| host      | user                       | plugin                |
+-----------+----------------------------+-----------------------+
| %         | john                       | mysql_native_password |
| localhost | debian-sys-maint           | caching_sha2_password |
| localhost | mysql.infoschema           | caching_sha2_password |
| localhost | mysql.session              | caching_sha2_password |
| localhost | mysql.sys                  | caching_sha2_password |
| localhost | root                       | auth_socket           |
+-----------+----------------------------+-----------------------+