The Sentinel, was the name given to the creature that protected an underground city on the planet Alashan. The creature was the byproduct of an ancient complex within the city. The power of the complex caused the creature's presence to give off an extremely large energy signal that could be detected at a distance, even by the sensors on an astromech droid. The creature and the complex had been seemingly created by an ancient civilization native to Alashan, whose technology and culture had been lost to time. For some unknown reason, they had sealed their city's walls with a massive metal barrier, locking the Sentinel and their ancient technology away from outsiders.
The Sentinel possessed near-supernatural powers and strength. Among its arsenal was the ability to fire a concentrated superlaser, as well as the ability to modify its size and to teleport. After being released from its prison by curious Rebel archaeologists, the Sentinel began to slaughter what it perceived as unwelcome intruders. Eventually, due to efforts of Rebels Luke Skywalker and Leia Organa and Imperials Wil'm Grau and Anarine, the ancient complex was smashed into disrepair, apparently killing the seemingly invincible monster.
Sometime before the formation of the Republic, a culture of technologically sophisticated beings from the planet Alashan developed a power source with the ability to destroy foreign objects a hundred thousand kilometers from their planet's surface. Any record of the source of the power was kept with hieroglyphic writings that adorned the culture's massive underground city. To protect the huge metropolis, the Alashans created a complex called the control center. The complex became the source behind the powerful energy that was known as the Sentinel creature. With power to protect the city, as well as the ability to leave the area to attack potential intruders, the Sentinel was a formidable protector of the massive capital. Along with the power to operate a destructive superlaser, the Sentinel could teleport to any place in the city, as well as modify its shape to either fill a doorway or fit itself into small spaces.
When the Rebels first entered the massive structure, they found it deathly silent, and compared it to a tomb of sorts. The city was buried five kilometers under the ground and sealed with a large metal door, and the Sentinel creature was locked within the confines of its home, unable to leave.
Sometime around 0 ABY, Rebel archaeologists arrived on Alashan, believing it to be a dead world and hoping to find technology that could aid the fight against the Galactic Empire—rumors of the ancient Alashan civilization had survived through the years, and the Rebels decided to follow up on those rumors. Sonic scans from the archaeologists revealed a huge underground city within the dead soil of the world. Digging down five kilometers, the archaeologists found a huge metal barrier. Knowing what untold riches the place could hold, the archaeologists broke through the wall, not knowing what it held behind it. In the following time, the Sentinel was freed from his prison and began to seek out the intruders to Alashan. The monstrous creature hunted down the entire team and slaughtered them one by one, leaving their dismantled bodies lying inside the structures they had erected.
After missing three routine communications, Rebel scouts were sent to the archaeological station to check on the Rebel team. Scouts Arlo Tyre and Wadie Firestone came upon the destroyed site, discovering the slaughtered archaeologists and their habitat domes broken apart from the inside out. As Wadie checked his sensors, he found an immense energy field inside the main habitat dome. Arlo Tyre approached the dome with practiced caution, but as soon as he found himself in front of the entrance, a concentrated blast of energy from the Sentinel creature ripped through his body, killing him. Seeing that his partner was surely dead, Firestone rushed back to his Y-wing, hoping to escape the powerful force. Unfortunately, as soon as he got his ship off the ground, the Sentinel released another blast of energy, destroying the ship and keeping his appearance unknown for the time being.
The Sentinel continued to remain close to the city until it sensed two ships entering the atmosphere of Alashan. The first was the Staraker, a ship with experimental shields and speed that had been stolen from the Imperials by a team made up of Luke Skywalker, Leia Organa, and Mici Shabandar. The other was an Imperial cruiser intent on capturing the Staraker. The Sentinel fired a blast into space with deadly accuracy, destroying the Imperial cruiser. As the Staraker dived desperately, the Sentinel fired another blast at the ship, but the experimental ship's special shields were able to deflect some of the blast, keeping it from being totally destroyed. However, the ship was critically damaged and plummeted to the planet's surface.
Additionally, it seemed that several of the Imperials had survived their cruiser's destruction by evacuating in escape pods, and the Sentinel resolved to hunt down all of the intruders. Pinpointing the crash of the Rebel ship in a section of hardened lava, the Sentinel blasted away the hardened lava to get to the damaged ship. Crawling into the Staraker, the creature found Mici, but she rendered no life signals, and it tossed her aside, leaving the ship alone. The beast rushed back to its home, finding that the intruders had already entered the city. The Sentinel killed Eger Djambo, a stormtrooper placed as a sentry outside the entrance, and reentered its home. The beast immediately found another stormtrooper, Voss, and ripped through his armor, throwing him from one of the city's high towers. The Sentinel then pinpointed the main group and advanced upon them. However, concentrated blaster fire from the group collapsed the tunnel on top of the creature, stalling it temporarily.
Unfortunately for the Rebels, the Sentinel proved almost invincible and survived the landslide. Sneaking throughout the base, the creature tried to sneak up on the intruders one by one. The Sentinel was able to sneak up on Leia Organa, but just as it made to jump upon her, Luke Skywalker swung down and pulled her from the creature's grasp. With his prey swinging far away from him, the beast found another target in the Imperials Wil'm Grau and Anarine. The beast tracked them down to a tower within the city, but the Imperials were ready for it. The two men rigged the tower with explosives, and as soon as the creature entered, the supports exploded, collapsing the 200 meter tower on top of the beast. However, the power of the Sentinel was unmatched, and he pushed the pounds of rubble off of him and prepared to finish the two Imperials.
However, just as the Sentinel was upon them, it sensed that the Rebels had found the city's main complex. Knowing that the complex was the source of its existence and understanding that it needed to protect the structure at all costs, the beast teleported away from the two men and back to the complex. The creature also reduced its size so that it would minimize collateral damage. Entering the building, the beast found Ensign Kyril Lopaki bearing down on Luke and Leia with a blaster pistol. The Ensign turned and fired on the beast, hoping that its reduced size meant that it was less powerful. However, the beast still retained its awesome power and swatted Lopaki aside, killing him.
With Lopaki dead, the beast advanced on Luke and Leia. However, the young Jedi was not going to go down without a fight, and he brought his lightsaber to bear. The power of the saber managed to damage the creature's hand. Unfortunately for the Jedi, the Sentinel recovered from the attack and struck out at Luke, knocking him unconscious and flinging him across the room. The creature advanced on Leia next, but before he could reach her, Anarine and Wil'm Grau arrived to save the day, firing wildly into the room. Several of the blaster bolts hit consoles in the complex, staggering the creature. The intruders realized that the room was the creature's weakness, and so they began to destroy the complex. The Sentinel cried out in pain, grabbing Leia and trying to crush her within his grip. However, just at this moment, Luke revived and stabbed the Sentinel through the chest with his saber.
The thrust of the laser sword disrupted the matrix that gave the creature form and created a backlash loop into the complex. The strength of the energy resulting from the creature's death created a massive explosion, leaving the room in flames, and the intruders thrust from the room. After several days, the group was able to dig its way out of the rubble and make its way back to a ship. The Rebels and Imperials believed the complex and the Sentinel destroyed, as the lights throughout the entire complex had turned themselves off following the incident.
The Sentinel was an energy creature, reptilian in appearance. It generally assumed a massive form and enjoyed toying with its enemies. During an invasion by intruders upon the city, the beast delighted in slowly tracking down its prey, and as the intruders tried to fight back, it seemed to flaunt its invincibility by taking blaster shots full on. This reaction was only seen different when the creature faced Luke Skywalker and his lightsaber, which generally hurt him. In this instance, the beast took a defensive stance, striking out wildly.
The creature also generally seemed to enjoy murder and mayhem. It was known to laugh appreciatively when killing, and made its kills in a very gruesome manner, tearing the victim's body apart. Additionally, when the beast first searched the Staraker, it left a scene of destruction within the inside of the ship. This same destruction was seen when the Sentinel first attacked the archaeologists, as it ripped apart their habitat domes from the inside out, seemingly only for its own destructive needs.
The Sentinel possessed incredible powers given to it by the power of the Forever control center. It had enormous strength, and could easily rip through stormtrooper armor with its bare claws. Additionally, the beast had the power to teleport from place to place, which it demonstrated when it felt that the complex was in danger and transported itself back to its source of power. Finally, the Sentinel demonstrated the ability to change its size when it entered the complex, shrinking its size so that it would minimize damage to the delicate structure.
The Sentinel, albeit unnamed, first appeared in "World of Fire!" storyline in the comic book series Star Wars Weekly published in the Star Wars Weekly 107 on March 12, 1980, and was later identified as such in "The Guardian of Forever!" storyline published in the Star Wars Weekly 113 on March 12, 1980. Both comics were written by Chris Claremont and illustrated by Carmine Infantino and Gene Day.
A similar creature known as the "Night Beast," appeared in The Night Beast, a comic strip story arc written by Archie Goodwin, illustrated by Al Williamson and published in 1982. Goodwin was an editor on the "World of Fire!" and "The Guardian of Forever!" storylines.
- The Complete Star Wars Encyclopedia, Vol. II, p. 261