Wesker,Chris Redfield and Jill Valentine,

Wesker declared that only one with the true capability of being a god could ever deserve that right. Wesker then stood at the window of Spencer's castle and further pondered this new revelation. Spencer's own arrogance manifested into Wesker himself, who decided to carry out his former master's vision of shaping the world with an new and advanced race of humans. Wesker saw that the influence of a pharmaceutical corporation was not true power and insufficient to bring about the godly status he sought. He therefore discarded Umbrella's inferior power and decided to take over the very plan Spencer himself started, with another pharmaceutical company as his base for enacting the plan. Just then, Wesker's old enemies, Chris Redfield and Jill Valentine, entered Spencer's hiding place. They had been hunting Spencer and Wesker, the last of Umbrella's leadership, under the command of the BSAA, and were given a reliable tip to Spencer's whereabouts. They infiltrated the castle, hoping Spencer would lead them to Wesker, but instead found a dead Spencer with a smiling Wesker. The villain took their sudden arrival as a sign: "The weak would always resist the will of the Chosen." A battle immediately ensued. Using his powers, Wesker overcame the two of them combined, outmatching their gun fire and hand to hand skills.
Tossing aside Jill after she failed to turn a knife on him, Wesker sought his revenge on Chris once and for all. However, before he could deal the finishing blow, Jill sacrificed herself by tackling him out of the window, causing the two of them to fall into the chasm below. The BSAA searched for the bodies for months, but were never successful in recovering them, and the two were marked as deceased. In fact, the two survived and Jill was captured by Wesker. After giving Jill the medical treatment she required, Wesker went back to his alliance with Tricell.

Ozwell E. Spencer's Death

In the following years Spencer went into hiding, making sure he had little contact with the outside world. His hiding place had been his European estate, a castle along the coast of an Atlantic ocean. Chris Redfield and Jill Valentine were given information from a reliable source on Spencer's location, hoping to arrest Spencer and get information on Wesker's whereabouts. Minutes before they arrived, Wesker himself paid a visit to Spencer, who was expecting him, much to Wesker's shock. Wesker realized that Spencer had been in control of everything that had been occurring over the years, even his own actions, and the two discussed Wesker's origins. Wesker was the result of genetic experimentation with the Progenitor virus along with thousands of others, known as the "Wesker children."
Spencer revealed that his goal was to create a new breed of humans -Albert included- and thus become a god over a new world. However, Albert was the only one that survived out of other individuals who were "manufactured" such as him, and the research itself was destroyed along with Raccoon City. As Spencer stood from his wheelchair to confront Wesker face to face, Wesker violently thrusted his hand through Spencer's chest, whispering to him that the right to become a god was now his, and had never been Spencer's. Wesker viciously removed his hand from his chest, allowing him to topple over. As Jill and Chris entered the room, they unexpectadly found Spencer's corpse, with Wesker's bloodstained figure standing over him. After a battle in the Spencer Estate, Wesker and Jill disappeared, and were presumed dead. Spencer's corpse was left lying on the floor of his castle.