And because LEGO bricks silently and telepathically command us to reconstruct absolutely every facet of human civilization in their blocky image, here's Bryce McGlone's take on xenomorph designer H.R. Giger's Li II. The sheer child's-birthday-ruining power of this sculpture alone demands mass production. Build one at the Giger Bar for bonus thematic resonance.
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SAnd for more rectangular plastic body horror, behold Ian Gowan's chestburster. Hat tip to Jones Foyer, who pointed this out in this post about some toothy cakes.