Head Alien

The leader of the Alien Horde has no specified name, and so is referred to as "the Head Alien." His sole purpose is to pursue the boy named Spaceman Spiff and destroy him, while using his own established syndicate of aliens and monsters to achieve this goal. He possesses a great loathing for the boy, and is shown to be ruthless—willing to go to any lengths to annihilate his sworn enemy. The Head Alien's greatest setback is his lack of limbs (hence the floating chair), which prevents him from combating Spiff himself; for this and other reasons, he is often driven to extreme fury, not caring about anyone or anything else who stands in his way. Therefore, as the events of the "Dimension" saga take place, the Head Alien focuses his intentions on one target—namely Calvin, identified as the enemy, Spiff—and seeks to eradicate him once and for all.

ATTACK ON CALVIN'S HOME
The Head Alien and his group make their first appearance in the flesh just as the boy has begun to claim victory over the attacking snow goons; he surveys Spiff's appearance and taunts him, while wondering why he isn't in his usual uniform. Evidently the boy is shocked beyond belief, as he fails to provide his usual snappy retorts. Instead, the Head Alien sends his forces after the boy and his two allies as they retreat into the house—while he himself observes the resulting carnage from outside. He issues threats to his enemy as he apparently continues to resist, before entering the house himself soon afterward, ambushing the rebellious trio upstairs while flanked by the rest of the alien horde.
 * "There is no point in trying to resist us! Hand over Spiff, and we shall leave your sullied world!" -the Head Alien, to Hobbes, who is defending Calvin and Susie

The tiger shields both humans as they become cornered, and the Head Alien makes clear that all they want is Spiff's surrender; after a moment or two, the boy steps forward and seemingly gives himself up, causing the Head Alien to express high regard for his boldness. However, the alien then becomes shocked as the girl suddenly throws a water balloon at the horde, causing all of them to recoil and the leader to fall backward out of his chair, which prevents him from quickly pursuing the trio as they run past. The Head Alien latches onto one of his allies and catches up with Spiff in another room—just before a bright light suddenly appears from a watch of some kind, subsequently causing the targets to disappear as the light fades away.

Unable to pursue his enemy, the Head Alien curses the group's failure and ponders what to do next, considering that they have no idea where Spiff and his allies went. After searching the surrounding area, the Head Alien eventually comes across a human named "Moe" walking nearby; taking into account this human's apparent enmity with the horde's own target, he orders one of his forces to grab the human for interrogation. The Head Alien questions Moe, believing that he must have some idea where Spiff has gone, and tells him that his life will be spared if he divulges this information. However, Moe states that if he did know the boy's location, he would not talk. Irritated, the Head Alien orders the human's annihilation, but is then interrupted by the arrival of a shadowed figure claiming to know where Spiff has gone.

ONSLAUGHT ON YOSHI'S ISLAND
The horde uses the Zok Death Sloop to reach the provided destination, while the Head Alien keeps the human Moe imprisoned on board—curious as to why Spiff's personal foe would defend him, and considering the possibility that there does exist a loyalty between them. Upon arriving at "Yoshi's Island," the Head Alien takes his entire squadron to shore, ordering the Tyrannosaurus rex to capture the girl for leverage; afterward, the horde makes its presence known to the boy and his tiger, surrounding them both with their own forces, including the snow goons. The Head Alien further taunts Spiff for not being up to his usual standards, before initiating the attack—during which he acts as supreme commander, overseeing the battle and giving orders to his group. After a few minutes, the Head Alien grows irritated with the tiger's constant interference and orders his elimination; however, the boy (now donning a cape and hood) suddenly flies in and rams into everyone, once again causing the Head Alien to fall out of his chair and onto the ground.

Thoroughly infuriated at this point, the Head Alien retreats to his own vessel, as several more Zok Death Sloops keep the boy and his allies occupied. He observes his enemy's mannerisms and strategies, taking into account the boy's determination to come to Miss Derkins' rescue, and arriving at the obvious conclusion. Remembering the surprising loyalty shown by Moe earlier, the Head Alien tries a different approach; he uses the ship's bombing capabilities to get Spiff's attention, before suspending the restrained captive Moe miles above the water—threatening to drop the human and cause him to drown if Spiff does not give himself up. However, the boy simply casts aside the threat, making clear that he does not much care for Moe after all. No longer interested, the Head Alien drops him into the water and uses the Zok Death Sloop to begin bombing Spiff out of the ocean and across the island constantly, determined to successfully annihilate his enemy this time, with the rest of the alien horde's assistance.

Just as victory becomes almost certain, however, the Head Alien is contacted and ordered to retreat, by he who provided the location of Yoshi's Island in the first place. Completely confused and angry, the Head Alien protests, but soon complies. He retracts his forces and they all vacate the island—though not without exasperation, seeing as the Head Alien was about to accomplish his goal at last. Now conscientiously doubtful of this "Eggman Nega's" true motives, the Head Alien later decides to pay him a visit.

Aftermath
At the same time, the alien leader also gives thought to his own admitted incompetency as a threatening opponent for Spiff; observing his own lack of actual limbs and need of a measly floating chair, he decides to also put forth a request for a mechanical body upon arriving at Nega's base of operations. After being assured that Nega does intend to see the alien horde's goals through in the end (though not entirely convincingly), the Head Alien makes clear to him that in order to achieve this victory, he now needs a controllable mechanism specifically designed for Spiff's demise; Eggman Nega tells the alien leader that the process may take time, but he will soon have his requested body. The Head Alien then departs, not completely satisfied with Nega's assurances, but willing to patiently wait for his new body nevertheless.

Hours later, the Head Alien is at the docking bay when Nega comes running out of the tower, looking furious. It is revealed that their apparent captive, the professor, has evidently escaped. What is more, their location has been unveiled to their adversaries, and so it becomes clear that they must flee. The alien leader suggests that they go to their hidden refuge, and Nega agrees, stating that they will need all of their resources there, in order for their backup plan to move forward. Upon departing in the Zok Death Sloop, the Head Alien also receives orders to send his troops to the Infernal Machine, for verification of its true condition—to which he replies that it shall be done.

THE POCKET DIMENSION CRUSADE
On the way to their destination, the Head Alien notices that Nega appears to be slightly unwell; evidently his condition is steadily worsening as time goes on. This is taken into consideration as the Head Alien lands the Zok Death Sloop at their hidden refuge, and they disembark. He then asks Nega what their plan is now that the Infernal Machine is lost, only to hear this matter cast aside as a "minor setback." This irritates the Head Alien, who states that his own plans for locating and destroying Spaceman Spiff are now also compromised, and he grows angry over Nega's lack of concern; however, Nega then tells him to stay out of the way, as he enters the compound to inspect the status of his captives.

The Head Alien remains outside for a short while, as his own second-in-command later approaches. At this time, the Head Alien reveals his full awareness that the Infernal Machine is in fact still running, and declares that the alien horde's plans have been foiled by Nega long enough. He knows that Spiff and a contingent of his new allies have entered the wormhole generated by the Infernal Machine, and so gives the order for their troops to go in after them and capture Spiff, primarily. The alien leader opts to remain behind and continue his surveillance on Nega in the meantime, and reflects on his own plans for the boy once the horde has him—for he knows that it was Professor Membrane who was tasked with creating his new body...

Time passes, and the Head Alien hears back from his troops; apparently directly capturing Spiff will prove more difficult than they anticipated, seeing as he and his allies have powerful "emeralds" in their possession. The alien leader accepts this, and tells them to move forward with Plan B. As the transmission ends, however, the Head Alien notices a rocket approaching, and quickly slips out of sight, realizing that more enemies have arrived. (editing shall recommence soon)

