After development of the Proto-Tyrant (T-001 Type) was cancelled close to completion due to its defects, its data was collected and further research and development began on another model which would resolve previous imperfections. After administering the t-virus variant for Tyrant creation to another test subject, the research team led by William Birkin was able to significantly refine the T-002, ensuring that the t-virus did not act to the full extent of its power and erode the subject. They successfully preserved a sufficient level of intelligence for following and executing commands. It displayed a high measure of perfection with combat abilities and was officially christened "Tyrant", the official name of the t-virus and its development project, as a symbol of the power it exhibited and to represent its status as the perfect B.O.W. utilizing the t-virus.
For several years, the T-002 was developed as a "combat model" by the Arklay Biological Weapon Research Team. Meanwhile, Dr. Birkin had transferred from the facility and began development of a "humanoid model", the Tyrant (T-103 Type) which had a more human appearance over the "00" series. However, the control aspect of the Tyrants concerned the researchers. In order to improve them and demonstrate its superior capabilities, a vast amount of live combat data in the field against veteran soldiers was required as feedback. Following the leak of the t-virus in the Arklay Laboratory in May 1998, Umbrella began to assess the situation and form a plan to ensure the T-002's precious combat data could be collected.
The Mansion Incident
During the events of Resident Evil, Albert Wesker ordered the Tyrant to slay the remaining members of Raccoon City’s S.T.A.R.S. The Tyrant wounded Wesker, leaving him to die. The remaining S.T.A.R.S. members engaged the Tyrant in battle before escaping the mansion.
Although it had exceptional fighting capabilities, Umbrella didn't intend to mass-produce it, instead using this model as a base to improve upon. It is stated in Wesker's Report that, in theory, only a small proportion of people injected with refined T-Virus directly into their DNA could become a Tyrant, while the rest would only become normal zombies.