Devil

The Devil, in the various human cultures and religions of Earth, is a supernatural entity who is considered to be the personification of evil. Different cultures have given the Devil a variety of names, including Satan, Asmodai, Beelzebub, Lucifer, and Mephistopheles among others. In addition to the Devil of Earth mythology, a number of alien cultures had similar beliefs in an evil being similar to the devil.

When first meeting with James T. Kirk in 2268, the Klingon Kang told Kirk that the Klingons had no devil, but they were quite aware of the habits of the human devil. (TOS episode Day of the Dove.

The being known as Lucifer was later proved to be based on an actual person. The Megan Lucien visited Earth during the early 17th century, he barely escaped Earth with his life while other Megans who visited the planet were executed in the aftermath of the Salem Witch Trials. Lucien would be recorded in human history as the entity in Lucifer. In the 23rd century, the USS Enterprise (NCC-1701) visited Megas-Tu and met Lucien and the Megan race. It was then they learned the full story behind the Witch Trials. (TAS episode The Magicks of Megas-Tu)

Delcara once told Captain Jean-Luc Picard that she was the "Guardian Angel of the Dammed." Picard replied that Satan was their guardian angel.

In the 24th century, a female con artist learned that the Ventaxian mythological being known as Ardra was expected to return soon. She studied the legend of Ardra very carefully, and appeared when Ventaxian legend said Ardra would reappear. During her encounters with the crew of the USS Enterprise (NCC-1701-D), she tried to convince the crew that she was also the Devil and the Klingon entity Fek'ihr. (TNG episode Devil's Due).