There aren't a whole lot of Henson/Alien/Giger connections or cross overs, but the artist
best known for designing the Xenomorph in 1979's "Alien" definitely inspired the Henson team.
Using one of of his many portraits as an example,
you can clearly see the influence his work had on the creation of Farscape's Pilot.
The most direct connection in a Muppet production is from the Muppet Babies episode "Nanny's Day Off," in which Baby Animal is seen being awakened from a stasis chamber following a number of establishing shots from "Aliens."
Below are the two paintings Giger made in 1976 that drew Alien director Ridley Scott to hire Giger. His creature would go on to terrify warrant officer Ripley through 4 films and audiences around the world for decades to come.
“Necronom IV”“Necronom V”
You can read more about Giger and his work at Roling Stone.