Commodore

Commodore was a military rank, typically applied in a pro tempore or transitional fashion, for a officer in a Navy who commands several ships in addition to his or her own. The rank may be given as a per-need field promotion (and be rescinded as such), or as a permanent promotion in keeping to an order of ascendancy to that of Admiral status. Indeed, Commodore is typically classified one rank below that of Rear Admiral, and one above Naval Captain.

Galactic Empire
An Imperial Commodore commanded a Naval Squadron, consisting of several Lines. In the Empire, a Commodore was considered a junior member of the Admiralty, and was respected as such by their subordinates. It was the equivalent of an Imperial Army Brigadier.

New Republic
The New Republic Starfleet would bestow the title and rank of Commodore upon the senior or lead officer of a tributary or allied homogenous force attached to their fleets for a campaign. They would do this so as not to confuse their own ranking structure by making the officer in question a bonafide Admiral. Its equivalent in the New Republic Army and New Republic Starfighter Corps was Brigadier General.