sysadmin
Members of the sysadmin fixed server role can perform any activity in the server. By default, all members of the Windows BUILTIN\Administrators group, the local administrator's group, are members of the sysadmin fixed server role.
See Also
Reference
Concepts
Permissions of Fixed Server Roles
Other Resources
sp_helpsrvrole (Transact-SQL)
sp_helpsrvrolemember (Transact-SQL)
sp_srvrolepermission (Transact-SQL)
Security Considerations for Databases and Database Applications