terminator

A person or thing that brings something to an end or concludes it.

"She acted as the terminator of the complex negotiations."

A character or symbol indicating the end of a data item or statement.

"A semicolon acts as a statement terminator in many languages."

A fictional, powerful, often robotic entity designed to eliminate targets.

"The film features a relentless cybernetic terminator from the future."

The dividing line between the illuminated and dark parts of a celestial body.

"Astronauts observed the lunar terminator from orbit."