GENERAL GUIDE: this applies to all creatures. Certain creatures (looking at you humans) have MANY variants, but all creatures have a mutant and a husked version.
TO MAKE A HUSKED CREATURE: inject the creature with calyx extract. duh.
TO MAKE A MUTANT CREATURE: after you husk a creature, shoot it with syringes of !!UNSTABLE CALYX EXTRACT!! Be aware that if you are a smart person and are using the disguised as husk buff to do this, this WILL aggro the husk unless you space out the syringes carefully. This aggression will only last so long, as very quickly the creature will become a Husk Cocoon. The aggresion doesnt persist, but the husk cocoon will aggro on you and chase you. this is not very good if you dont have robes, as a mutant will be dumped on your face in ~40 seconds. Depending on the size of the creature, it will have one of 2 cocoon types. As a rule of thumb, if it can walk (humans, crawlers, mudraptors, etc.) it will become a bipedal spindly cocoon. If it cant, (threshers, bone threshers, hammerheads etc.) it will become a larger finned cocoon. when it hatches, you get mutant creatures!!!

SPECIFICS (aka humans)
DIVING SUIT HUSKS: Either husk someone wearing a diving suit, slipsuit, abyss suit, combat suit, PUCS, or exosuit, or reverse lockpick one of those onto an existing normal husk. You dont get the suit back if you kill the husk. If you mutate one of these, theres a high chance they just become a normal mutant human husk, same as if you mutated a normal human. I have heard that theres a small chance to make a unique mutant, but I have not observed this firsthand.
BOIL HUSK: appears to sometimes be made from skipping the normal husk stage and simply mutating a non husked human. Practically a reskinned cocoon, and will become a mutant the same.
MUTANT TREE HUSKS: These can all be obtained from the mutant human husk. When dealing anough damage to a mutant husk, it can split into two husks, the Torso husk and the Leg husk. The leg husk kinda justs runs around somehow despite having no spinal cord. The torso husk behaves like a crawler. When dealing enough damage to a Torso husk, its head can fall off and become a Headcrab husk. The headcrab husk is unique because it will literally leap onto a non husked persons head and try to get at their spinal cord. The victim will be able to control themselves and talk, while a status called "Burrowing" starts building up. If this hits 100, they will be killed and become a Zomopan (Zombie-Europan) if the victim is shot in the head while the Headcrab is burrowing, it will die and they will be freed. The Zomopan will be get more intelligent pathfinding than other husks and be able to use guns... somehow? (dev if you see this PLEASE comment why they become smart) If you dont have a gun on hand, it can be helpful to handcuff the victim, as the Zomopan will keep the handcuffs when it finishes burrowing. The Zomopan can become a Stalker under conditions i am not sure of, and the Stalker can shoot "headpods" which will burst into Headcrab husks. In short: Dont get head from a husk. This whole part is starting to feel like an elaborate half-life reference.