Goblins are an engineered species of (mostly) small humanoids with pointed ears, born from early alchemical experimentation.
Whilst a typical goblin is small, green, and has pointed ears, due to the nature of their creation, goblins come with all sorts of mutations & colorations.
The Goblin Concoction
The Goblin concoction is the source of all goblins. A goblin is born when sufficient fuel is provided for a goblin concoction. Creating a concoction is usually done by taking a body part from an existing or deceased goblin and throwing it into a grand cauldron alongside other alchemical reagents at hand. These reagents then affect the properties of the created goblin.
Experimentation by different goblin tribes has led to the creation of many differently aspected subspecies. Among these are hob, arcane, and aquatic goblins though many variants within each sub-species exist due to the often scavenged reagents put into concoctions.
Each goblin tribe has at least one concoction brewing at all times, adding reagents as more of their kind are needed or resources allow. The brewing station is usually the most well-protected object in the tribe.