"Tyrant" is a code name for biologically engineered super soldiers created and used by the sinister Umbrella Corporation. Tyrants make appearances as boss characters in most of Resident Evil games and the desire to create an obedient bioweapon lies at the core of the series' storyline.
There are many types of Tyrants as the result of several different experiments. Following the discovery of the Progenitor virus, the Umbrella corporation’s founders become eager to create a Bio-Organic Weapon (BOW) that is both powerful and capable of following orders. Prior to the events of Resident Evil Zero, Umbrella used the Progenitor virus to create the Tyrant virus (T-virus), which they believe can be used to manufacture powerful organisms. A problem with the virus’ compatibility with humans set the project back, as only humans with a very rare genetic makeup are capable of mutating into potent and manageable life forms. Umbrella eventually overcame this setback by resorting to using clones of Sergei Vladimir, one of their executives who happens to be genetically compatible. The events of Resident Evil Zero and Resident Evil chronicle the Umbrella Corporation's development of the Tyrant prototypes, the T-001 and T-002. Though the early Tyrants are defeated in their first encounters, Umbrella manages to use the battle data from those defeats to produce other, more efficient Tyrants in the later installments of Resident Evil. Numerous Tyrants have been created throughout the story line, each with its own defining characteristics. A revamped version of Tyrant also existed in Resident Evil 5 during the game's development, but not in the finished product.
Outside of the Resident Evil series, there is a Tyrant card in the NDS version of SNK vs. Capcom: Card Fighters Clash. Prototype Tyrant player character was cut from the character roster of the crossover fighting game Marvel vs. Capcom 3: Fate of Two Worlds.
A Tyrant monster also appears in the third Resident Evil movie, Resident Evil: Extinction. After being bitten by an enhanced zombie, Dr. Sam Isaacs tries to subdue his mutation; however, he's shot for insurbodination and immediately revives as a Tyrant. Compared to the Tyrants from the games, Isaacs retains his mental faculties and personality even after his mutation.
- As "Tyrant" is the name of Umbrella's product, humans who exhibit enhancements from the t-Virus, but were not intended s (Morpheus, for example), are not to be considered Tyrants. The same goes for dobermans infected through a secondary means; they are "zombie dogs", rather than Cerberus.
- Although no Tyrants were present in Resident Evil 5, there was supposed to be a Tyrant-like creature infected with Uroboros in the initial stages of RE5 development. Excella Gionne was originally scripted to die by, literally, the hands of this creature by getting stabbed in a similar way by Wesker's Rhino Charge.
- On most occasions of the games in which they appear, a rocket launcher is required to finally destroy a Tyrant.
- Tyrant is present on one of the cards in SNK vs Capcom: CardFighters DS.
- The Gas Zombies from Dead Rising 2, have a close look to most tyrants, as they sport a greyish skin color, white eyes and having their hearts exposed.
- The Supreme Hunter from Prototype is also similar to the Tyrants.
- The Tyrant R featured in Showdown 3 scenario, is the only Tyrant (except for Nemesis 3rd mutation) to survive a rocket launcher hit.