Master LLC is the entity registered with the state of Delaware or another state that recognizes series. Part of the series LLC structure (see series LLC definition). It is required to have a Master LLC registered with Delaware before creating any Series LLCs associated with it. The Master LLC is like a parent, or “mothership” LLC. The Master LLC is the only entity of the Master Series structure that is listed on the Certificate of Formation and the certificate will designate that the LLC has the ability to designate protected series. The Master LLC is the protective “fence” around its internal protected series. The most common structure of a Series LLC is to have the Master hold no assets and conduct no business activities other than designating protected series under its “umbrella”.