10. Play God
For every Peter Parker there's a Seth Brundel, yet even when the biological engineering is reserved for non-humans nothing ever seems to go quite right. Of course, this only applies up to an extent: stem cell research is a valuable medical resource, but the lengths horror movie protagonists go to in the name of science sometimes beggars belief. While the events of Jurassic Park probably remain the greatest folly within the biological horror subgenre, there are plenty other cautionary examples: the genetically engineered super-intelligent sharks in Deep Blue Sea and killer sheep in Black Sheep; the ultra-violent human/animal hybrid in Splice; and yet more animal-people in Island Of Lost Souls. Inevitably, the creations end up turning on their creators, often in highly ironic circumstances. Dr Moreau's control over his experiments collapses when he breaches the very laws of human decency that he's been imparting onto them; the female scientist who created the hermaphrodite Dren in Splice as a substitute child is eventually made pregnant by her/him. The kindly John Hammond of Jurassic Park survives, but not without causing a few horrible deaths and nearly getting his grandkids eaten by dinosaurs.