Ustanak

Ustanak (which means "Revolution" in Serbian) was a unique B.O.W. (Bio-Organic Weapon) developed by Neo Umbrella and built from the ground-up to specifically to hunt down and capture Jake Muller in order to retrieve his blood which would help with the creation of an enhanced version of the C-Virus. The human host which served as the basis for the Ustanak was an incredibly infirm individual and as such they welcomed the chance to become something powerful and dangerous, therefore their transition into this beast was far less painful for them than most.

It appeared like a large, muscular male covered in scars from various implants and performance-enhancing surgeries. It also retained some hair follicles which is rare for a B.O.W. It's face was a twisted mess held together with a few large staples - it wore a face covering in most instances in order to obscure this fact.

The transformation was gradual, happening over a number of weeks. With each day, the beast grew in size and strength. Unfortunately due to an accident the right arm was left unusable. The course of action Neo Umbrella decided to take was amputation, as their previous research with the C-Virus showed that the limb would simply regenerate, or the body would mutate in some other way to compensate. This didn't happen however, so the Ustanak was unleashed with only one arm.

Eventually a prosthetic was developed by the team which was strapped onto its stump and served as a grabbing and slashing tool - useful for capturing and attacking. Various additional prosthetics were also developed which the creature knew it could swap them out such as a large mining drill arm or a minigun-like weapon. It can even make use of various arm attachments in a combat situation by swapping them out on the fly which shows its level of intelligence was greater than most C-Virus infected.

Although its intelligence was impaired, it would still listen to and take instructions from Carla Radames who was one of the ones instrumental in its creation.

It's many encounters with Jake Muller and Sherry Birkin proved that it was a capable beast and extremely resilient, but also fairly intelligent - using its skills to track down the duo and re-acquire them after they've escaped its grasp. In fact, it managed to follow them across the oceans from Edonia to China. However, it was in China that it met its demise - but not without putting absolutely every effort in to succeed. It simply rose again and again from defeat - even when it was dropped into a pool of molten metal. Even though it seemed defeated, it's charred form rose out of the pool and attempted to kill Jake once again. However, due to the damage to its body its internal organs were now exposed which allowed Sherry to target its heart and kill it for good. Despite this, it still tried to live on but its death was now inevitable.

The way it hunts Jake Muller is reminiscent of the Nemesis T-Type or the T-103 (known as Mr. X) which were B.O.W.s developed by Umbrella which had specific targets to hunt down and kill or capture.