The Quarren, sometimes insultingly called "Squid Heads," were a sentient species of humanoid, squid-like beings. Their homeworld was the planet Mon Cala, where they shared the world with the Mon Calamari. Their relationship was generally peaceful, though not without its tensions.

As a squid-like species, the Quarren possessed four tentacles on their faces, specifically protruding from their lower jaws. Their skin-color varied, encompassing shades of orange, salmon, tan, pink, and purple. Distinctive features included a pair of deep turquoise eyes, finned hands with suction cup-tipped fingers, and small tusks near their mouths. What appeared to be gills on the sides of their faces were actually hearing organs located within the two long protrusions.
Being native to the aquatic planet Mon Cala, Quarren were excellent swimmers and felt most at ease when submerged in water; they were most comfortable in liquid environments. They were also capable of walking upright on two legs and sitting. As a defense mechanism, they could expel clouds of black ink in battle. This ink could also be released if a Quarren was fatally wounded, such as being cut open at the mid-section by a lightsaber. They also released ink during nightmares while they sleep. Low-humidity environments could harm their skin and nasal passages, leading off-world Quarren to use products like moruga nut oil and take extremely hot showers.

Quarren were a sexually dimorphic species, exhibiting male and female sexes. Their physical forms resembled those of humans. The Quarren Jethpur communicated in Quarrenese, but were also proficient in Galactic Basic Standard.
Much like the Mon Calamari, the other sentient species with whom they shared Mon Cala, Quarren typically wore clothing covering most of their bodies, leaving their heads exposed. However, the Quarren pirate Kragan Gorr donned an Imperial officer battle armor helmet.
Both the Quarren and Mon Calamari could undergo cybernetic modifications. Furthermore, hybrids between the two species existed by or before 146 BBY.
The Quarren shared their planet, Mon Cala, with the Mon Calamari, another prominent amphibious species. Both preferred constructing their cities underwater. However, the tensions between the two species made living together difficult at times. Around 392 BBY during the High Republic Era, the Quarren Orlen Mollo went back to his home to help negotiate the end to a territorial dispute. Later in the High Republic age, one of Supreme Chancellor Lina Soh's Great Works plans was to negotiate a treaty between the Quarren and Mon Calamari. A large number of Quarren also lived on the estuary moon of Trask; Quarren and Mon Calamari colonized the moon, hoping to escape Mon Cala's politics.
Around the time of the Trade Federation's Invasion of Naboo, a Quarren Senator named Tikkes represented Mon Cala in the Galactic Republic Senate. During the Separatist Crisis, Tikkes switched his allegiance to the Confederacy of Independent Systems, and the Loyalist Tundra Dowmeia replaced him in the Galactic Senate. In general, the Quarren species tended to side with the Confederacy during the Clone Wars, though some Quarren supported the Republic. Quarren engineers were employed by the pro-Confederate Free Dac Volunteers Engineering Corps. The Quarren Isolation League advocated for Quarren independence.
The Mon Calamari Knights fought against Separatist Quarren. During the Clone Wars, the Separatists, through the Karkarodon advisor Riff Tamson, incited conflict between the Quarren and the Mon Calamari. Following the assassination of the Mon Calamari King Yos Kolina, the Quarren, led by Chieftain Nossor Ri, challenged his son Prince Lee-Char's claim to the throne. Encouraged by Tamson, Ri demanded new leadership and a chance for the Quarren to govern Mon Cala. This triggered a civil war on Mon Cala: the Separatists supported the Quarren Isolation League, which attempted to conquer Mon Cala with the Confederacy's military assistance, while the Republic backed the Mon Calamari. Before the fighting began, Senator Padmé Amidala and her Jedi bodyguard Anakin Skywalker visited a Mon Cala city to try and mediate peace between the two warring species.
However, the Quarren launched a preemptive attack on the City of Mon Cala using Separatist AQ-series battle droids, but the Mon Calamari's Jedi and clone allies repelled them. The Quarren then launched a counter-attack with Hydroid Medusas, massive jellyfish with electrified tentacles, which overwhelmed the Mon Calamari and Republic forces. Soon after, the Quarren captured the Capital. The remaining Mon Calamari and Jedi were forced to retreat. Despite the victory, Ri felt uneasy with his new Separatist allies after Tamson followed Count Dooku's orders to enslave the Mon Calamari population.

Quarren forces then participated in a manhunt for several enemy fugitives including Prince Lee-Char, Senator Amidala, Skywalker, and the Jedi Ahsoka Tano and Kit Fisto. Despite resistance from the fugitives and the arrival of Gungan reinforcements, the Quarren and Tamson's Separatist forces succeeded in capturing the fugitives. However, the Quarren-Separatist alliance dissolved after Nossor Ri discovered that Tamson intended to crown himself as the new ruler of Mon Cala. Ri stopped Tamson's plan to execute Prince Lee-Char, who wanted to restore relations between the Mon Calamari and Quarren. The Quarren then joined forces with the Mon Calamari, the Republic, the Jedi, and the Gungans in a combined effort to expel the Separatist invaders from Mon Cala. Following Tamson's death, the Quarren accepted Lee-Char as the new King of Mon Cala.
After uncovering the sinister Separatist plot and re-aligning themselves with the Mon Calamari, the Quarren and Mon Calamari fought as allies to uphold peace, from the final stages of the Clone Wars and throughout the Galactic Civil War. Early in the Imperial Era, Quarren and Mon Calamari fought alongside each other against the Empire's invasion of Mon Cala. The Quarren Chadkol Gee lost his family to the Empire during the occupation of Mon Cala. Later, by joining together, the two species were able to wipe out the occupying Imperial garrison. During the [New Republic Era](/article/new_republic_era], the Quarren and Mon Calamari finally had their long awaited peace.
Following the Battle of Crait, Resistance agents travelled to Mon Cala for help in the battle against the First Order, earning the ire of the now-General Nossor Ri, who did not want more destruction brought upon the peoples of Mon Cala. Chadkol Gee, however, contacted the First Order about the Resistance mission, resulting in a First Order fleet appearing over Mon Cala. After Gee's crime was revealed and King Ech-Char decided to give the Resistance the reinforcements they sought, Ri chose to sacrifice himself to allow the Resistance a chance to escape and to make up for what Gee had done. After Ri was killed and the Resistance escaped, First Order forces landed on Mon Cala to enact revenge upon the Quarren and Mon Calamari for daring to help the Resistance, further convincing Gee that he had been right all along.

Numerous Quarren individuals could be encountered across the galaxy in various professions. Christo, Tikkes, and Tundra Dowmeia served as senators in the Galactic Senate during the final days of the Galactic Republic. These senators used bathing pools to keep their skin moist. Orlen Mollo was a jovial Quarren who served as a Supreme Chancellor of the Republic, holding the Office of the Chancellor jointly with the human Kyong Greylark. With Greylark remaining on Coruscant, Mollo was free to travel the Outer Rim aboard the Alif-class Longbeam Paxion to help his citizens. Meeting Jedi Knight Gella Nattai after an impressive piloting display during the skirmish in the Eiram system, Mollo slapped her on the back in greeting, which she took as odd behavior for a Chancellor and a Quarren.

A Quarren migrant by the name of Lauli Wahlo ran a noodle shop in Coruscant's underworld, while another, Amit Noloff, was a member of the Iego council. During the Galactic Civil War, Tessek worked as a book-keeper for Jabba the Hutt on the planet Tatooine. During the Clone Wars, many Quarren were employed by Jabba Desilijic Tiure to serve him as guards. The former slave Quarren Palabar, along with his companions the Wookiee Greybok and the Weequay Hatchet, participated in the New Republic's liberation of Kashyyyk. The Quarren Kragan Gorr began his career as part of Grox's pirate crew and later commanded his own pirate group, the Warbird gang.
Kara Xoo was a Quarren Nihil Tempest Runner during the High Republic Era. Quarren Heavy Gunners served as soldiers in the Alliance to Restore the Republic. A Quarren nicknamed "Squawk" was a Republic agent who worked with the Jedi Seanand Mostima during the High Republic Era. The Quarren Hennix was a Padawan in Luke Skywalker's Jedi Order.
The first appearance of the Quarren was in Star Wars: Episode VI Return of the Jedi," which debuted on May 25, 1983.