Captain
Outside of military contexts, the title of captain designated an individual responsible for the operation of a starship. Within military organizations, for example, the Imperial Navy or the Royal Naboo Security Forces, a captain signified a high-ranking officer with significant leadership duties. Pirate leaders, such as Hondo Ohnaka, Lassa Rhayme, Ought-Six, and Sidon Ithano, were referred to as captains of their respective pirate groups. However, pirate captains could face removal from their position through mutiny, as demonstrated by the overthrow of Silvo by his First Mate Brutus.
Military organizations
Galactic Republic
During the Republic Era, the Galactic Republic incorporated the captain position within its Judicial Forces. The Republic Defense Coalition during the High Republic Era also utilized captains, who were authorized to command their own RDC starships. In 22 BBY, the government established a formal army and navy. This newly formed Republic Military, consisting of clone troopers originating from the planet Kamino, employed the rank of captain in both its army and navy. Clone trooper officers holding this rank were known as Clone Captains, although the role wasn't exclusive to clone officers.
Many clone navigation officers, including some with the rank of captain, displayed a single-row plaque featuring two red squares and one blue square (arranged from left to right). Within the army, Clone Captains were in charge of companies comprising 144 troopers and reported directly to a Clone Commander. Due to the flexible command structures often adopted by Jedi Generals, some captains worked directly with their Jedi superiors. A prominent example is Clone Captain Rex, who commanded the 501st Legion's Torrent Company and served as the primary subordinate to Jedi General Anakin Skywalker.
Clone Captains, when wearing standard Phase I armor, were initially identified by maroon markings on their white armor. However, many captains began to personalize their armor to express their individuality, represent their company's identity, and prevent easy targeting by snipers.
Confederacy of Independent Systems
The rank of captain was also present within the Confederacy of Independent Systems. In the Separatist Droid Army, both organic officers and droids could attain this rank. Rackham Sear, a male Kage Warrior, held the position of captain in the Confederacy military. The Separatists also deployed commando droid captains; one such captain served at the Citadel.
The Confederacy navy also made use of the rank. Captain Mar Tuuk was a member of the Confederacy navy, and oversaw the Ryloth blockade from his Lucrehulk-class Battleship.
Galactic Empire
Captains were present in both the Imperial Navy and Imperial Army of the First Galactic Empire. A stormtrooper captain from the army acted as a military advisor to Queen Trios of Shu-Torun.
The rank's Imperial insignia plaque for navy officers featured three red squares above three blue squares. Security officers had three blue squares followed by two red squares. Army officers wore three red squares followed by one blue square, and a single row of six yellow squares denoted rank for security officers.
The term could also describe someone in command of a vessel, regardless of their official military rank. Thrawn served as captain of the Chimaera while holding the rank of commodore. He continued to advance in rank, eventually becoming a Grand Admiral.
Alliance to Restore the Republic
Within the Alliance to Restore the Republic, captains served in both the army and the navy.
The insignia for a Rebel captain consisted of two pips positioned vertically. The pips' color (red, blue, or green) indicated the individual's branch of service.
This practice was also established in the rebellion's early stages.
First Order
The First Order employed captains in its navy and Army. Cardinal and Phasma were two captains serving in the army's Stormtrooper Corps.
First Order ranks were indicated by a combination of uniform color and arm insignia, worn on the uniform's left sleeve. First Order captains wore gray uniforms with a black armband trimmed in silver. The armband featured the name of Dillon, a celebrated Imperial hero from the Galactic Civil War, inscribed in silver Aurebesh letters.
Resistance
The Resistance included captains in both its army and navy.
The rank badge for Resistance captains displayed a colored vertical line, with red indicating personnel in the army and blue for those in the navy.
Within the Resistance Army, the rank of Captain was subordinate to that of Commander.
Other militaries
The rank of lieutenant was present in the military forces of E'ronoh. Jerrod Segaru served as a lieutenant and advisor to the E'ronoh royal family.