William Birkin was born exceptional—and Umbrella noticed early. By the time he reached adolescence, his intelligence was already being measured, categorized, and monetized. At fifteen years old, in 1977, Birkin was recruited directly into Umbrella Pharmaceuticals, bypassing normal academic channels entirely. He was offered a place in Umbrella’s executive training program at the Arklay research school under Dr. James Marcus, There, Birkin met Albert Wesker. The two formed a rivalry disguised as friendship. Both were conditioned to accept Umbrella’s ethical framework: that progress justified sacrifice, and that humanity was a resource like any other. The Arklay school closed abruptly on July 29, 1978. Two days later, Birkin and Wesker were reassigned as senior researchers at the nearby Arklay Laboratory.

On his first day, Birkin was introduced to Lisa Trevor, a living artifact of Umbrella’s cruelty—imprisoned since 1967. Birkin was granted approval to pursue experimental splicing of Umbrella’s Tyrant Virus prototype with genetic material derived from Ebola samples acquired under the guise of vaccine research. Birkin’s modified strain kept hosts alive—aggressive, brain-damaged, contagious. The modern t-Virus was born. Yet praise was short-lived. In 1981, Umbrella hired Dr. Alexia Ashford, a ten-year-old prodigy believed to be Umbrella royalty. Her arrival shattered Birkin’s self-image. For the first time, he was no longer the miracle child—just one of many. From that point forward, Birkin stopped seeking approval. He began seeking dominance.

Determined to solve the t-Virus’s remaining flaw—natural immunity in roughly 10% of the population—Birkin pioneered Bio-Organic Weaponry. His most notable success was Hunter α, a hybrid organism created by bonding reptilian DNA to a fertilized human egg via the t-Virus. During this period, Birkin formed a relationship with fellow researcher Annette. They married in the mid-1980s and welcomed their daughter Sherry in 1986.

By 1988, the Tyrant Project stalled. Intelligence degradation remained unsolved. That same year, Spencer ordered Dr. James Marcus assassinated. As Marcus lay dying, Birkin confiscated his mentor’s research notes, absorbing decades of work into his own data set. From that point onward, history would label Birkin a “creator of the t-Virus.”

Desperate for a solution, Birkin acquired NE-α parasites from Umbrella Europe—organisms capable of overtaking brain function. After repeated failures, he used the parasite on the only compatible host remaining: Lisa Trevor. The parasite failed. But Lisa survived. Her body absorbed the parasite’s DNA, and a new Progenitor variant embedded within her genome. Birkin immediately understood what he was seeing. This was not a weapon. This was evolution. He named it Golgotha.

Spencer was intrigued. Umbrella constructed NEST, a massive subterranean lab beneath the chemical plant outside Raccoon City, completed in 1991. Birkin was installed as chief researcher, with Annette at his side. Throughout the 1990s, Golgotha research advanced—but Umbrella never elevated Birkin to the executive tier. Birkin noticed. He began planning his exit. When the t-Virus escaped into the Arklay Mountains, Birkin quietly ensured the training school was destroyed.

In early September, Birkin sabotaged the P12A waste processing facility, flooding it with failed test subjects and destabilizing viral containment. The t-Virus escaped into Raccoon City’s infrastructure, contaminating water treatment plants and hospitals. Umbrella mobilized. On September 22, 1998, the USS Alpha Team—led by HUNK—breached NEST.

Birkin heard the alarms and grabbed the sample case and ran—only to be surrounded.

“I’m not letting you freaks take this. Back away!”

He raised his pistol. They shot him down. As HUNK’s team retrieved the case, one vial rolled free and shattered near his hand. Bleeding. Betrayed. Replaced. Birkin injected himself with Golgotha. As Hunk and his team left him.