SecuRich
SecuRich is a library of stored procedures which add security features to MariaDB and MySQL. It is mantained by Darren Cassar, and can be downloaded from securich.com.
Its main purpose is to emulate roles, but this feature is supported in the server since MariaDB 10.0. However other interesting features are available via SecuRich, such as the ability to block a user, clone a user or set an expirable password.
To use SecuRich features, its stored procedures should be used instead of the usual security-related SQL statements. For example, drop_user() should be used instead of DROP USER. However, if a combination of SecuRich procedure and normal SQL statements is used, SecuRich can reconciliate its tables with the system tables.