Fleshcrafting
Fleshcrafting, also known as Fleshwarping, is a term used on /tg/ as a catch-all to a specific form of dark magic and/or mad science that revolves around augmenting, transforming, shaping, sculpting and creating life, typically through a horrific amalgamation of alchemy, surgery and, if present, sorcery. Common uses of fleshcrafting include producing grotesque grafted biological augments or weapons, and creating monsters from corpse-pieces or living beings, usually to serve as servants of some description. This field of interest is usually restricted to races and individuals of the evil NPC variety, as it is generally seen as being too morally reprehensible (or overpowered) to allow PCs to have it.
D&D
Fleshcrafting has been used in the background of various monsters and even races since Dungeons & Dragons was first a thing. The Flesh Golem, the Broken One, the Bulette, the Owlbear and many more are usually said to be the result of mad wizards or dark artificers playing around with the secret of life.
In Advanced Dungeons & Dragons 2nd edition, PCs were pretty much restricted from using this style, although the Anatomist kits for the Necromancer (Wizard) did eventually allow the player to build flesh golems and, technically, the Xixchil could touch upon it through its racial ability to self-improve by grafting on armor and weapon-limbs. Several unique NPC monsters also existed to represent victims of flesh-crafting experiments.
In 3rd edition, PCs could actually get involved in this themselves. The principles of creating grafts were first introduced in the 3e Fiend Folio, then expanded upon in "Lords of Madness", which presented the Graft Flesh item creation feat, several new aberration grafts, and the Fleshwarper, a Prestige Class specialized in augmenting itself and others by grafting on bits of defeated monsters. The Half-Golem template technically represents one branch of fleshcrafting study.
In Pathfinder, several archetypes for the Alchemist make use of Fleshcrafting, whilst it is an "artform" mastered and wielded by both the drow and the derro. The drow in particular have created a number of unique, horrific monster species through their established procedures for warping living organisms to their liking.
WH40K
In Warhammer 40,000, there are several examples of this form of artifice.
The absolute champions of it of the Haemonculi of the Dark Eldar, and several other Dark Eldar units actually represent the fruits of their labor at sculpting flesh into new servile forms.
The Magos Biologis of the Adeptus Mechanicus also experiment in this field, as their teachings lead them to prefer bio-grafts and organic augmentations over the traditional cybernetics of their fellows.
The Gene-seed of the Space Marines is effectively a form of fleshcrafting, as it uses various genetically cultured biological augments to transform a lowly human into a powerful Adeptus Astartes.
The Tyranids' entire species is based on fleshcrafting, constantly absorbing new genetic material and analyzing it to provide new ways to modify and augment themselves on a physical and species level.
And, last but not least, let's not forget about Mr. Fabulous who's been desecrating CAREFULLY PERFORMING SCIENTIFIC EXPERIMENTS UPON anyone or anything that had the misfortune PRIVILEGE to get in the same room as him for the last ten millenia in order to create 'the perfect human being'.
Other Games
In Deadlands, "Patchwork Science", a primitive form of fleshcrafting that amounts to making Flesh Golems is mentioned in the second of its monster manuals, although Marshals are told emphatically that this is NOT to be allowed into player hands.
The Tzimisce from Vampire: The Masquerade have the Vicissitude discipline, which grants them the power to shape flesh and bone at low levels, become a puddle of sapient Vitae, do all sorts of weird stuff and even become a monster.
Skaven Clan Moulder in Warhammer Fantasy specializes in this, mostly to create bigger and better breeds of rats.