"If you must know, my name is Osmund Saddler, the master of this fine... religious community."
— Saddler, introducing himself to Leon.
Osmund Saddler (オズムンド・サドラー,Ozumando Sadorā?) was a bio-weapons research chief who resided in an isolated Spanish region. He was the leader of Los Iluminados, a neopagan cult and paramilitary organisation, of whom its worshippers referred to as the Prophet Saddler. In the early 2000s, Saddler's leadership saw the cult become a dominant force in the region through the weaponisation of the mind-controlling Plaga parasites to suit his plans for world domination. He was killed in 2004 during a US-STRATCOM mission to rescue Ashley Graham, the President's daughter who Saddler's organisation had taken hostage.
How Saddler discovered the existence of the mind-influencing animal species, Las Plagas, is a mystery, given his non-Spanish name betrays his nature as an outsider. Equally so is how he was able to obtain materials for bio-weapons research and fund a paramilitary organisation.
Saddler entered the region in the early 2000s, intent on possessing the Plagas to gain financial and military influence on the world stage. The Plagas, as recorded in local folklore, had been hidden in ancient ruins below the First Castellan's new castle. To gain access to the ruins, Saddler took the guise of a holy man, and manipulated the young Ramon Salazar into giving him access by converting him to his new cult, then making him feel guilty over his ancestor's actions and seek redemption. Through Salazar, Saddler was able to gain access to the ruins with the aide of an excavation team. Expecting to find only carcasses, Saddler and his team were surprised to find years later that the excavation team had inhaled spores which regenerated into full-grown Plagas.
Saddler began research on the rejuvenated parasites, and had them genetically modified to be more resistant to attempted removals in a project led by Dr. Luis Sera.A new subspecies was also engineered, which would be dominant among the parasites' social collective and force hosts to obey the wishes of the dominant hosts, who were themselves free of mind control.
The conversion of Father Bitores Mendez, the village priest and chief, marked a significant expansion in the cult's power. Fr. Mendez was the village priest as well as its elder, leading both the political and religious affairs of the region. By turning him into a disciple, Saddler was able to convince almost the entire rural community to abandon their Catholicism and turn to the cult. Injected with Plagas as part of a cleansing ritual to wash away sin, the villagers soon fell under Saddler's control. When this process was complete, he used them as a means of keeping people from endangering his plans, ordering them to kill any outsiders entering their region.
With his local power cemented and Plaga-based bio-weapon research underway, Saddler moved on with his plan for world domination. Dr. Luis Sera, not a follower of the cult and secretly working as an investigator, sent an e-mail containing his research findings on the Plagas and how to destroy them to a friend of his after discovering he had been secretly implanted with an egg, which he removed. Ada Wong discovered this e-mail during a mission, and passed it on to her new employer, the so-called "Third Organization". This group then tasked Jack Krauser with retrieving a Dominant Plaga sample. Saddler was concerned about how a third party was aware of the Plagas as it was a threat to his plan, but allowed Krauser the dominant sample in return for his temporary services, and factored Krauser into his plan while still considering ways to eventually have him killed.
In 2004, Krauser abducted Ashley Graham, daughter to the American president, and sent her to Saddler, who implanted her with a parasite. The plan was to use her as a way of influencing the President, perhaps through the parasitisation of other influential people, and allow Saddler control of American political and military affairs. In the event this plan was discovered, Saddler expected the paranoia over who is parasitised to cause the US to crumble, thereby removing them as a threat regardless.
The US government quickly covered up the kidnapping and began an intense investigation of its agents. Leon, one of the few to be cleared of suspicion, was sent out alone to investigate, and was captured and parasitised on Saddler's orders, possibly with the intention of sending him back to the US as Ashley's 'rescuer'. However, the intervention of Dr. Sera and Ada Wong caused significant problems to this plan, especially when Sera provided Leon and Ashley with drugs to slow the Plagas' growth rate while Ada later destroyed a warship and its Ganado crew. Krauser was able to prevent a rescue, however, when he successfully tapped into the US government broadasting frequency, allowing the militia to track a helicopter and destroy it. He later had it jammed, with only he and Salazar able to broadcast messages to Leon. Dr. Sera was also killed by Saddler in the castle to recover a Dominant Plaga egg he had stolen for Ada. However, in his stalling for Leon and Ashley's Plagas to hatch, Saddler nonetheless suffered the loss of both Mendez and Salazar, who were nearly irreplaceable, and was forced to retrieve Ashley on the Island, with the intent on Leon either being killed by U-3 or by Krauser when following.
Saddler placed Ashley in a capsule, unconscious, in the expectation of keeping her safe until her Plagas took control of them fully. Finding Leon alive after Krauser's death, Saddler considered keeping him as a bodyguard, and soon after had a second American helicopter shot down to prevent Ashley's capture. Close to Ashley's takeover, Leon and Ada cooperated in freeing her; Saddler was able to knock out Ada while she made a distraction for Leon and Ashley to use Dr. Sera's special equipment to destroy the Plagas in their bodies. Leon found his way onto a building underground construction, where Saddler had placed the tied-up Ada. After freeing her, the two worked together to fight him, though Saddler's parasite had already grown outside his body into a large and powerful creature. A rocket launcher used by the militia was captured by Ada, who gave it to Leon to fire. Saddler's parasite received a powerful hit and died; their lives co-dependent on one another, Saddler died with it.