Enrique Muñiz was a Starfleet crewman assigned to Deep Space 9 and the USS Defiant in the 2370s. He eventually became a good friend of Chief Miles O'Brien, whom Muñiz called jefe, Spanish for "chief". O'Brien affectionately called him "Quique". In his youth, Muñiz attended carnivals with his father. He had the same birthday as Jake Sisko.
In 2372, he was on board the Defiant when it rendezvoused with a Karemma starship in the Gamma Quadrant. When two Jem'Hadar attack ships attacked the Karemma, they tried to escape by entering the atmosphere of a nearby gas giant. The Defiant followed the ships into the atmosphere where it was fired upon and severely damaged. Miles O'Brien sent Muñiz to a Jefferies tube to assist Jadzia Dax. When the internal force fields began to collapse in that section, Muñiz managed to get out, but Jadzia was left behind.
Muniz later returned to engineering to help O'Brien and Stevens to repair the ship. When Worf arrived to take command of the ship after Captain Sisko, he criticized Muñiz and Stevens. O'Brien reminded him that neither of them had attended the Academy and were not used to be commanding a starship. Stevens and Muñiz later came up with a way to modify the deflector array to turn it into a phaser emitter. Their plan worked and the Jem'Hadar ship was destroyed. (DS9: "Starship Down")
In early 2373, Muniz was part of a Starfleet survey team from DS9 that traveled to the Gamma Quadrant planet Torga IV to assess the possibility of establishing a mining operation to extract some of the planet's rich deposits of cormaline. A Dominion ship crashed on the planet and was later followed by another who destroyed the team's runabout and landed Jem'Hadar troops. Muñiz was wounded by the Dominion weapons, but was saved by O'Brien and Worf and taken into the ship. The anti-coagulant in the Dominion weapons soon took their toll on Muñiz and his bleeding continued. O'Brien and Worf clashed after Worf told him that Muñiz was near death. As time went on, Muñiz soon lost feeling in his legs and became delusional, believing he was watching a carnival with his father. Muñiz eventually died of his wounds during the crew's attempt to use the ship's engines to escape.
After the Defiant arrived, rescued the crew and towed the Dominion ship off the planet and back to the Alpha Quadrant, O'Brien sat with Muñiz's body, performing a traditional Irish wake. He was joined by Worf who commented on its similarities to the Klingon tradition of ak'voh. (DS9: "The Ship")