Cryptosporidium

Cryptosporidium or Crypto for short is the main protagonist of the Destroy All Humans! series. He is a Furon alien invader, and the central agent of his species' operation to harvest ancient Furon DNA from the human race to ensure their continued survival.

History
Crypto's history is unknown up to the events of the games. He worked with Orthopox for quite some time before coming to Earth. His story can be divided up by the number of clones he's had.

Cryptosporidium-136
The first Crypto clone to appear in the game. He's sent to Earth to find Furon DNA, but is accidentally shot down by a missile in mid-launch in Area 42. Human soldiers surround the Saucer, and Crypto emerges out mortally wounded. He tries to fight back after crashing, but he collapses to the ground. His weapons and Saucer are taken and reverse-engineered by Majestic to develop new weapons. 136 is dissected and leads to the unlocking of the Furon genes and the creation of Majestic's Psi-Mutants. His capture is the reason Crypto-137 urges Pox to come to Earth. His remains are later destroyed by Crypto-137 so no more experiments can be performed on his "brother".

Cryptosporidium-137 (Destroy All Humans!)
Orthopox and Crypto 137 are alerted to Crypto 136's predicament and Crypto urges Pox to go and rescue him. Since their species is dying out from lack of pure DNA, and humanity's gene pool has buried in them, a strand of Furon DNA, thanks to a Furon being on "shore leave" millennia ago from destroying the Martians, Pox agrees to this to collect DNA. Their new destination is the planet Earth.

Crypto is sent to Earth to harvest Furon DNA from human brain stems, locate and rescue his previous clone, and spearhead a Furon invasion of Earth.

Crypto-137 first landed on Turnipseed Farm in 1957 to search for the dominant species on Earth, which led to him destroying an infantry unit of the US Army. He headed towards Rockwell in order to investigate human culture. Though this led to the discovery of experiments by the military on local cows. After several missions in Rockwell and Santa Modesta, Crypto and Pox become aware of the Majestic, and begin crippling government attempts to undermine their mission.

Majestic planned to control human minds to make them paranoid and aggressive, but Crypto stopped their plans and destroyed their base in Santa Modesta. He also found out about 136's fate in Area 42 and swore revenge. After destroying most of Area 42, Crypto headed toward Capitol City in order to hunt down General Armquist, but he crash landed in Union Town. Unlike 136, he survived this experience.

After that, Crypto kills Armquist after he stopping his attempt to unite the four divisions of National Defense under the Majestic's leadership against the Furons. Later, he assassinated the President and went after Majestic's leader, Silhouette, to end their resistance once and for all. She had a giant, 50-foot robot with Huffman's brain inside it waiting to attack, but Crypto manages to beat it, then takes out Silhouette at the Octagon. With that, the Furon invasion seemed inevitable for the human race.

Following Silhouette's death, the President seemed to be found alive and the invasion being proved a false alarm, but really, he is just a disguise for Crypto so he can set up "testing centers" across the nation to fight "toxic pollutants inside their minds". Those centers were really chambers to extract Furon DNA from the humans. In that moment, the Furons have already won the war, without the humans even knowing it.

Cryptosporidium-138 (Destroy All Humans! 2)
Crypto 137 died some time before 1969. His new clone, Cryptosporidium-138 was active from 1969 to sometime before 1979. He is the first Furon to have pure Furon DNA, which gave him improved mental abilities and fully functional genitalia which made some drastic changes in his personality.

KGB spies learned of the Furon takeover of America and plan to eliminate them and end their mission. They launch a nuclear missile to blow up the Furon Mothership and Pox with it, and try to assassinate Crypto in Bay City at the same time. Fortunately, he escaped with Pox, who has now become a downloaded mind stored in a hologram device. The two Furons now fight a war against the KGB, who are determined to destroy them and undermine their mission on Earth.

Along the way, Crypto joins forces with the Russian spy, Natalya Ivanova and eventually her partner and ex-lover, Agent Sergei, who are looking to uncover a conspiracy hidden within the KGB. They both share the same goal of protecting the human race, regardless of their different reasons for doing so.

With Crypto's help, the ancient enemies of the Furons, the Blisk were discovered and they have been manipulating the Soviet Union so they can transform the Earth into a new Mars, since the Furons wiped them out and reduced Mars to a desert. The transformation of Earth into a radioactive ocean world would kill all of humanity, leaving no more Furon DNA, dooming the Furon race to extinction.

After much effort, Crypto finally managed to kill all of the Blisk with the help of a virus Pox had made, though it came at the cost of Natalya's life. Soon after, Crypto had cloned Natalya and mated with her.

Cryptosporidium-138 (?) (Destroy All Humans! Big Willy Unleashed)
During the 70's, Crypto has left the presidency, broke up with Natalya, and moved to Harbor City, spending his days watching television.

He was brought back into service when he found out about Orthopox's fast food franchise, Big Willy's. He now has a new mission to defend the restaurant, as its primary source of meat is the human corpses of whom Crypto sucks the brain stems out of.

Crypto and Pox then work to promote their restaurant and eliminate the competition, Colonel Kluckin and all of his pawns and henchmen, with the giant Big Willy mech at his disposal. All of his missions lead him to places like Fairfield, Fantasy Atoll, and Vietmahl.

Following Kluckin's destruction in Vietmahl in an epic showdown between two giant mechs, Orthopox decided to give up the fast food business for good. Pox gives Crypto the money collected from the restaurant's proceeds, with which he intends to start his own business in a little town in Nevada.

Cryptosporidium-139 (Path of the Furon)
This Crypto clone was created in the mid-late 70's after 138 crashed his old saucer while "drunk flying". After the crash, the new clone opened a casino called the "Space Dust" (a parody of "Stardust Resort & Casino") in Las Paradiso that is soon a business success, becoming popular on the Strip. Pox believes Crypto has gone native and berates him for abandoning their mission.

Soon after, they discover that the local mob family has sent a spy to gather information on them. Crypto infiltrates their casino and drives out their customers, leading the mob to go to war with Crypto. He defeats the mob, destroys all their profits and takes control of Paradiso.

He begins to hear a voice instructing him in the Paths of Enlightenment and how to advance in those paths. Then suddenly, strange alien creatures attack the Space Dust casino. Pox identifies them as "Nexosporidium Warriors", whom are supposedly extinct. Crypto defeats them, in doing so, attracted the attention of the military. Crypto destroys them, and had to reluctantly annihilate all of Paradiso to erase any evidence of their being there, including the casino that Crypto worked so hard to build. They both surmise that someone is conspiring to eliminate them. Crypto vows revenge against whoever is responsible, and hide in Sunnywood to figure things out.

In Sunnywood, the duo assume that Curt Calvin, head of the Lunarian Church of Alientology, sent the Nexos and is another DNA harvesting Furon on Earth. With the help of a reporter on the supernatural named Veronica Stone whom he saved from the Lunarians, he learns of an inside man in the cult called "Deep Navel". Crypto works out a deal with this inside man, he gives him Calvin in exchange for a few favors done to get him closer to the cult's inner circle, but Deep Navel failed to keep his part of the bargain. Pox and Crypto decide to stage a "big alien arrival" to draw out Calvin. He confronts him to make him reveal his Furon form, suddenly a Nexo Walker steps on him (which reveals that he is human). Crypto destroys the walker and is suddenly shot with a tranquilizer dart and faints.

He awakens three days later in a monastery in the city of Shen Long run by a Furon martial arts expert called "The Master" who was the mysterious voice in Crypto's head. After a confrontation, he agrees to be his disciple to defeat Saxon, a former student of the Master who got power-hungry and now leads a local triad to oppose the Master, and the presumed source of all the misfortune that has befallen Crypto. After a few missions, the Master tells Crypto to hold a martial arts tournament to attract Saxon, but the Master lied so he can face Saxon alone. Crypto got back to watch Saxon kill the Master. Enraged, Crypto tracks Saxon and tries to destroy him, until Nexos came and vaporized him, proving he wasn't the one who attacked his casino in Paradiso. He escaped the Nexos, and learns from Pox that those Nexos were cloned here on Earth by an organization called Francodyne Industries. The two head off to Belleville, France to investigate.

In Belleville, France, Crypto and Pox go after the head of Francodyne Industries, Henri Crousteau, who is working on a virus to de-integrate Furon DNA from the human genome, which will result in the crumbling of the Furon Empire. After going on a few missions, Crypto stops the Nexo Walkers carrying the virus and destroys Crousteau who was in a giant, robotic squid. As Crousteau dies, Crypto learns that the Furons could make synthetic DNA, which means his mission on Earth was pointless, and someone was controlling Crousteau's Nexos from the Furon homeworld to attack Crypto's casino. They come to the conclusion that their true enemy was Emperor Meningitis. The two go back home to Furon to kill the Emperor.

On the Fourth Ring of Furon, Crypto tries to kill the emperor in his own palace but it obviously doesn't work. In the meantime, Crypto gets Pox a new clone body, sort of. His new body is a monkey. As a distraction, Crypto convinces the captured humans from the dome to riot in order to keep the palace security busy while they break into the palace. Crypto confronts the Emperor, who attacks using a giant, robotic bust of himself, but Crypto managed to defeat it.

After Meningitis's defeat, he roughly interrogates him, but he disintegrates into dust (the Emperor was 500 years old), infuriating Crypto more. All of a sudden, the Jade Talisman (the trinket that was given to him by the Master before he died) made the Master reappear before him, who revealed that he was behind all of his troubles, the Nexos attacking his casino, faking his death, exposing the synthetic DNA, everything, so he can become the Emperor. Angered by this betrayal, Crypto hints at Pox to slam him into a wall, which turned the Master into paste. Crypto is depressed that his whole mission was just one giant lie and eats some synthetic DNA, which made him hurl all over the floor. Pox tells Crypto that as long as synthetic DNA can make him lose his lunch, there will always be a reason to destroy all humans. Crypto goes back to Earth, while Pox stays behind to take Meningitis's place on the throne. They say their goodbyes, then the Furons come to greet their new Emperor.

Trivia

 * His accent is a reference to Jack Nicholson.