Can a database be created with no user and/or owner?
MySQL allows for a blank user with a blank password (anonymous access) to connect.

See Securing the Initial MySQL Accounts


  If accounts for anonymous users were created, these have an empty user
  name. The anonymous accounts have no password, so anyone can use them
  to connect to the MySQL server.




Besides that, MySQL does not have the concept of "database owner", like SQL Server and Postgres do. There is a privilege system, where users can be assigned various types of access to databases, tables, etc, with GRANT statement.