Oswell E. Spencer is the owner and co-founder of the Umbrella Corporation, a pharmaceutical drug company that secretly manufactures bio-organic weapons. Spencer's backstory is largely told through in-game files. Born into Europe's prestigious Spencer family with a wide education, he formed a close friendship with James Marcus and Edward Ashford while studying the emerging field of virology at university while becoming an apprentice of Mother Miranda's despite their opposing objectives. With knowledge he acquired, Spencer developed a god complex while plotting to force evolve humanity into a new superior race through genetic engineering and virology. His colleagues, James Marcus and Edward Ashford, join his company. Spencer seizes control of the company and its research by sending his subordinates to assassinate Marcus and Ashford. Spencer conducts some of his company's research in the Arklay Research Facility, located in the Arklay Mountains. He hires George Trevor, a famous architect, to construct a mansion to conceal the facility. Spencer's plans progress smoothly until Marcus returns from the dead through the Queen Leech as absorbing his genetic memory, motivated by revenge to destroy one of Spencer's luxury trains and cause a viral outbreak in the Arklay Research Facility. The outbreak spreads throughout the region, sparking the events of Resident Evil Zero and the original Resident Evil. The virus subsequently spreads to Raccoon City during the events of Resident Evil 2 and Resident Evil 3: Nemesis, prompting the U.S. government to attempt to contain the outbreak by ordering the destruction of the city.
After the city's destruction, Spencer attempts to disguise the incident as a government conspiracy by hiring top lawyers and false witnesses. His actions prolong the legal proceedings, and allow the Umbrella Corporation to stay afloat for five more years. Ultimately, Albert Wesker betrays Spencer by handing over secret documents to the U.S. government while providing personal testimony in court. Umbrella's business license is summarily suspended when most of its remains dismantled by U.S. government. Spencer becomes a wanted man and goes into hiding at his mansion in Europe. Wesker kills Spencer before Chris Redfield and Jill Valentine can arrest him. His first name is written as Oswell in the original version, but misspelled as "Ozwell" in the English version.