Serpentor
Serpentor is a fictional character from the G.I. Joe toyline. He was introduced in 1986 as a toy with an air chariot and introduced in the animated series that same year in the five part mini-series "Arise, Serpentor, Arise!" He took over the leadership of Cobra in Season 2. He was created through a breakthrough in cloning research by Dr. Mindbender from the DNA extracted from the unearthed remains of the most ruthless and effective military leaders in history, including Julius Caesar, Napoleon Bonaparte, Attila the Hun, Alexander the Great, Hannibal, and Genghis Khan.
Comics
Serpentor's character in the comics was somewhat different from the character of the cartoon. While the animated Serpentor was built to be a new, superior leader of Cobra, the comic counterpart was never intended to replace Cobra Commander, and was more akin to a general, someone to lead and inspire the troops, while Cobra Commander remained in power. However, this did not last, and Serpentor was ambitious, leading to power struggles between Serpentor and other members of the Cobra hierarchy. While there was initial tension between him and Cobra Commander, the latter was absent for much of Serpentors tenure in Cobra. Instead, Serpentor had to contend with the impostor Fred VII. Fred took an immediate dislike to Serpentor and the two were often at odds. Their rivalry eventually escalated in to the Cobra civil war, in which G.I. Joe sided with Serpentor to defeat the forces of Fred and the Baronness. The U.S. Government decided to support Serpentor, looking at it from the angle that they were supporting a monarch over a dictator. During this conflict, Serpentor met his end at the hands of Zartan, who assasinated him via an arrow. After this, his body was preserved in cold storage by Dr. Mindbender, for "purely scientific reasons." The body was later put inside the landlocked freighter and buried inside a volcano on Cobra Island, along with a number of "traitors", by the real Cobra Commander.
Being a clone, Serpentor's story does not end there. He was cloned again by renegade scientists and soon formed a secretive faction called The Coil. The Coil is composed of these renegade scientists and Cobra operatives who are dissatisfied with Cobra Commander. He now targeted both G.I. Joe and Cobra alike from the Cobra Island. He lured Mindbender back to his side, and launched a surprise attack, capturing Cobra Commander and several Joes. This resulted in a massive three way battle between G.I. Joe, Cobra, and the Coil. During the battle, several Joes were killed, Serpentor's forces were defeated, and Cobra reacquired the island. During a fight with Cobra Commander, Serpentor fell off a cliff, into the ocean below. His body was recovered by the former Coil general Overlord at the beheast of the Jugglers. Serpentor was then placed in suspended animation and the Jugglers instituted a number of brainwashing programs in order to have Serpentor eventually become their instrument. Their plans never came to fruition through, as following Cobra's defeat in Badhikistan, the Jugglers were assassinated by one of their own in General Mars Harring, whose true loyalities were with the mysterious Red Shadows organization. Claiming that the Red Shadows hated loose ends, Harring took a fire axe and broke open Serpentor's suspended animation chamber. Whether Harring killed Serpentor or turned the body over to the Red Shadows for some other purpose has yet to be revealed.
Cartoon
Serpentor was created largely due to a dissatisfaction among Cobra's ranking officers regarding Cobra Commander's ineptitude to lead Cobra. A dream inspires Dr. Mindbender to create a new leader for Cobra. This would later be retconned in G.I. Joe: The Movie where it was revealed that Cobra-La's ruler, Golobulus, gave Dr. Mindbender the blueprint for creating Serpenter via subconscious means. Unfortunately, due to the fact that G.I. Joe stopped Cobra from obtaining the vital genetic essence of Sun Tzu, Serpentor's personality was fundamentally flawed upon gaining consciousness. The genetic material they failed to capture was replaced by genetic material taken from Sgt. Slaughter. He proved to be much braver than Cobra Commander, but he was also every bit the egomaniac that the Commander had been, if not more so, and his courage often bordered on stubborness and foolhardy pride. Serpentor was usually portrayed as temperamental and prone to anger when things do not go his way. Unlike Cobra Commander, he appeared more likely to inflict physical harm on those that would displease him.
Later in G.I. Joe: The Movie, he would learn his true origins and join Golobulus and Cobra-La in its bid to transform Earth's populace into primitive slaves. To do so, they needed to capture the BET Machine. He gets his revenge on Duke for defeating him earlier by stabbing him with a snake javelin. By the end of the movie, Lt. Falcon avenges Duke by confronting Serpentor. Serpentor seemingly perished when Falcon causes his Air Chariot to go out of control.
That was, however, not the end of Serpentor. He appears again in the DiC-produced mini-series, G.I. Joe: Operation Dragonfire. In an unusual turning of tables, Serpentor's troops, including Destro, betrayed him when Cobra Commander returned. He was turned into a lizard and never seen again.
His trademark line was "This, I command!"
Controversy
Most fans express disdain when Serpentor was introduced into the G.I. Joe universe. Some felt that he takes away some of the realism to G.I. Joe (although the animated series frequently traversed into the realm of fantasy and science fiction) and a sign that it has jumped the shark. He is also criticized as a perfect example of a character forced upon the comic book and cartoon writers. Because there already is a Cobra leader, the writers had to come up with an explanation where a Cobra emperor would come from nowhere.