10 Creepiest Star Trek Aliens

First depicted in the Star Trek: The Original Series episode Wolf in the Fold, Redjac was essentially a homicidal cloud that nourished itself on the fear and anxiety created by the murders it committed.

Redjac was known on many worlds. On Earth, it was Jack the Ripper, an unnamed murderer in 1930s Shanghai, and an unnamed murderer in 1970s Kiev. In the early 22nd century, it killed eight women in the Martian colonies. In the 22nd and 23rd centuries it killed dozens of women on the planets Deneb II, Rigel IV, and Areglius II.

Enterprise’s chief engineer Montgomery Scott visited Areglius II on leave after an accident caused by a female co-worker. Dr. McCoy believed the planet's sexually permissive culture would help Scott overcome any resentment towards women. When Scott was suspected of Redjac's most recent crimes, Kirk suggested that this resentment might have been a possible motive.

However, Redjac was eventually identified as the real killer. Kirk, Spock, and McCoy then tricked the creature into revealing itself and Kirk had it beamed into deep space.