Thinking about some of the common morphology in T-Virus derived mutants in RE. Let's talk about
The V-ACT Process
The V-ACT Process occurs in those infected with T-Virus strains when the body is under extreme stress, such as injury or starvation. The process causes the body to rapidly regenerate tissue, allowing for the infected to become stronger, faster and deadlier.
The most famous results of the V-ACT Process are lickers (introduced in Resident Evil 2) and crimson heads (introduced in Resident Evil (Remake)). The most obvious shared traits are their sharpened teeth, claws and red skin (actually caused by their outer layer of flesh being shed, resulting in exposed muscle tissue)
Another notable result is the Super Tyrant (First featured in RE2). This is what happens when a tyrant is stripped of its trenchcoat limiter, allowing it to undergo continued mutation. Similar to the Licker and Crimson Heads, the Super Tyrant possesses extremely large claws. It also develops a rough, calloused skin texture. The fact that it doesn't shed its skin entirely like the licker may be due to the lack of necrosis.
Resident Evil 3 (remake) showed us a new design for the mutated Nemesis tyrant, taking on a quadruped stance, having its teeth grow substantially and (notably for the similarity to the Licker) losing its eyes or having them overgrown with new tissue. It would later undergo an even more extreme mutation, becoming essentially a huge mass of cancerous flesh with only the head being recognizable.
Finally, featured in Resident Evil: Dead Aim, Morpheus D Duvall enhances themself with a combination of the T and G viruses, the extreme regenerative properties of G being cancelled out by T's tendency to cause tissue death. As a result, Morpheus is mostly stable in their mutation. This is until they receive a serious amount of damage, at which point the T Virus' V-ACT Process kicks in. This causes their body to rapidly expand due to new tissue growth, becoming an engorged blob-like mass. This ultimately results in their death, as their body continues to grow well beyond its limits and ultimately explodes.
So, yeah, the V-ACT Process. A neat little piece of Resident Evil lore that ties together some of the franchise's most recognizable creatures.