My namesake, Necronom IV, although it technically predates the film (to be found in ''Necronomicon'', but as the book is expensive, quite readily online).
A different favourite, apart from the first Alien, is the deeply unsettling but alas unused design by H.R. Giger for the third film, whose pictures I have taken from a site called ''Bloody Disgusting''
A deeply disturbing creature, combining very primitively alluring female secondary sexual characteristics (almost steatopygous – the oldest human sculptural figures are women with prominent buttocks and breasts) and sculptural beauty (lithe, elegantly graceful limbs, a classically beautiful chin and fine lips) with extreme horror (litheness bordering on necrotic decay, an unnatural curve and disproportion of the limbs, pallor, the hideous elongated head). The biomechanics are beautiful and hideous at once and there is a certain unsettlingly feline or predatory grace in the limbs and claws.
A brilliant design and another example of unsettling use of inherited and inherent fears (balancing perfectly between an alluring siren and a subtly wrong, corpse-like thing to be fled from) and desires. Closely akin to the central fused figure of Necronom V (also ''Necronomicon'', see online if expense difficult), which possesses the unsettling head, female form and elegant aesthetic beauty and horror together.
I would dearly love to possess an accurate replica, if that can be said of something so beautiful and so horrible. I confess I would not study it late at night.