Illensans are a sapient, spacefarintg alien species whose external appearance somewhat resembles a cross between a skinny arthropod and a patch of yellowy ill vegetation. They have spiny limbs and membranous skin linking the upper and lower appendages and have been described as looking awkward in a spacesuit. Their physiological classification is PVSJ. Illensans are chlorine breathers and find both water and oxygen to be deadly toxic. They are also one of the three major races of the Galactic Union, along with Earth Humans and Tralthans, and are one of the many species represented among the staff of the Sector General space hospital.
- Sector General by James White
- Visitor at Large by James White