“I am afraid of my visions.” Thus spoke H.R. Giger, the artist whose paintings led to him being engaged by director Ridley Scott to design the xenomorph for the first Alien film in the late 1970s.

The “District 9,” “Elysium” and “Chappie” director captioned the Instagram post simply “Alien Day,” with on-image text identifying the woman as Newt. A child in “Aliens,” James Cameron’s 1986 sequel ...