Renz, a male human lieutenant, held a position of authority within the garrison defending the Galactic Empire's shield generator bunker on the moon known as Endor. This occurred during the events of 4 ABY. During that time, the Alliance to Restore the Republic dispatched an Endor strike team with the mission to deactivate the shield generator, a crucial step in their plan to destroy the Death Star II superweapon that was protected by the shield. The strike team infiltrated the bunker, successfully capturing Major Hewex, Renz's superior officer. However, Renz, along with a contingent of stormtroopers, intervened and compelled the rebels to surrender.
Following the rebels' removal from the bunker, an army composed of native Ewoks launched an assault on the Imperial forces stationed there, leading to the sealing of the bunker's entrances. While confined within the sealed bunker, Renz and Hewex received communication from Han Solo, a rebel operative who had cleverly disguised himself as an Imperial. Solo successfully deceived the Imperial officers into believing that the rebels had been vanquished. Consequently, Hewex instructed Renz to unlock the bunker's rear entrance. This action allowed the rebels to infiltrate the bunker, ultimately leading to its destruction and paving the way for the Death Star's annihilation.

During the Galactic Civil War, Renz, a male human, served the Galactic Empire as a lieutenant, fighting against the Alliance to Restore the Republic. Together with his commanding officer, Major Hewex, he commanded Tempest Force, a legion of Imperial Army troops garrisoned on the Forest Moon of Endor with the purpose of guarding the shield generator bunker. This bunker housed the shield that protected the Death Star II superweapon as it underwent construction in orbit around the moon. Consequently, the Imperial officers assigned to the station were highly skilled, with many giving up significant posts to serve on Endor.
In 4 ABY, an Alliance strike team was deployed to Endor to disable the shield generator. This would allow the Alliance Fleet to attack the Death Star. Aided by the native Ewoks of the moon, the strike team managed to infiltrate the bunker through a hidden entrance, surprising Hewex and several of his soldiers, forcing their surrender. As the rebels began setting up detonite charges to destroy the bunker, they were interrupted by Imperial reinforcements, a part of a scheme orchestrated by Galactic Emperor Sheev Palpatine. Colonel Dyer, the first Imperial to confront them, was knocked into the generator by the rebel Han Solo. Subsequently, Renz arrived with a squad of stormtroopers, forcing the rebels to surrender and rescuing Hewex and his men.

The stormtroopers then escorted the captive rebels out of the bunker, only to be met with an attack by a large army of Ewoks. After numerous officers retreated back into the bunker, the doors were sealed, trapping Renz and Hewex inside, safe from the ongoing conflict. After a certain time had passed, the two received a viewscreen communication from an All Terrain Scout Transport driver, who informed them that the battle had concluded and that the victorious Imperials required reinforcements to pursue the remaining rebels.
Renz and Hewex reacted with joy at the news, and Hewex instructed Renz to open the back door, allowing three squads to be dispatched as reinforcements. However, the message was a trick orchestrated by the disguised Solo, and the three squads that exited the bunker found themselves surrounded by rebels and Ewoks. The rebels then entered the bunker, forcing a disheartened Hewex and his men outside before planting their explosives and successfully destroying the shield generator. This allowed the Alliance Fleet to destroy the Death Star and achieve victory.
Renz was attired in a black Imperial officer's uniform, which included a belt, a cap adorned with an officer's disk, gloves, and boots. He carried a DL-21 blaster pistol when apprehending Solo and the other rebels.

Barrie Holland played Renz, though uncredited, in the 1983 original trilogy film, Star Wars: Episode VI Return of the Jedi. Holland had previously portrayed an Imperial officer in several scenes with Darth Vader actor David Prowse, including Palpatine's arrival on the Death Star II. He was then instructed by an assistant director to change into a black Imperial officer's uniform and speak with director Richard Marquand. Marquand offered Holland the role of Renz, as they had previously collaborated on the film Eye of the Needle.
The interior bunker scenes required a day and a half of filming and were shot on Stage 8 at Elstree Studios on March 23 and 24, 1982. Renz's line was originally written as "That is correct, rebel scum!" in response to the rebels' realization that they had walked into a trap, but it was shortened on set. In some takes, Holland attempted to deliver the line with an American accent instead of an English one. Due to the line, cameraman Alan Hume gave Holland the nickname "Rebel Scum" while on set.

During the first take of the scene, Harrison Ford, portraying Han Solo, playfully slapped Holland in the face and responded "What did you call me?" after Renz's line calling Solo scum. Holland described the scene as challenging due to the small set and the need for precise timing so that Solo turned to face Renz's gun. A timing light was used to signal Holland when to enter the set, and he experimented with running in on different beats between one and ten after the light in different takes, eventually finding eight to be the perfect timing.
Due to the limited visibility caused by their costumes, the actors playing the stormtroopers who arrived with Holland depended on him being in the correct position so that they could find theirs. After many attempts, Holland and Ford finally got the take after discussing it over coffee. Although Holland viewed his Star Wars role as simply another job, he believes he was fortunate to be in the right place at the right time to secure the role of Renz and what he considers a memorable line of dialogue. In his brief appearance, he feels he successfully portrayed Renz as a commanding officer whose ruthless demeanor exemplified the power of the Empire.
In current Star Wars canon, Renz's name was first officially used on a card in the 2014 Topps Star Wars: Return of the Jedi 3D Widevision set of trading cards, released by The Topps Company, Inc. in 2014. The name originated in the Star Wars Legends continuity, where it first appeared on a card in the Endor Limited set of the Star Wars Customizable Card Game, produced by Decipher and released in 1999.
A separate card in the 2014 Topps Star Wars: Return of the Jedi 3D Widevision set incorrectly attributes the combined lines "Freeze, you rebel scum!" to a single commander, merging Dyer's line from the film with Renz's. This error is also present in Return of the Jedi: Beware the Power of the Dark Side!, a 2015 adaptation of Return of the Jedi by Tom Angleberger, in which Renz is given the combined lines. In "The Battle of Endor and the Fall of the Empire," published as part of De Agostini's Star Wars Encyclopedia series on June 29, 2021, the names of Renz and Commander Igar are mistakenly swapped in a pair of image captions.