In the books of Kim Stanley Robinson, Terminator is a city on Mercury.

Terminator’s construction is ingenious. Metal rails circle the planet on the northern forty-fifth latitude. Set between the rails are metal cylinders that expand in the heat of the Mercurial day. The city is set on these rails. As the tracks expand in the sun, the city is forced along the rails to where they have not yet expanded at about three kilometres an hour. This keeps the city within the terminator of Mercury, the rotating band of dusk between freezing night and incandescent day.

Track laying on Mercury started in 2142, with rolling construction (by necessity) throught the 2150’s.

Terminator is either the only major city on Mercury, or simply the only city on Mercury. We never learn if there are more cities, but there are some underground refuges, scientific posts, power facilities, and at least one art gallery. Terminator’s police force is known as the spasspolizei. The spasspolizei enforce the many restricting rules and laws in Terminator. The Mithraists have plenty of power in Terminator government. The main feature of Terminator is the Dawn Wall, the easternmost wall. It is terraced, and lined with buildings. The higher the terrace is, the smaller it will be, and the more important the buildings will be. The offices of the Lion of Mercury, the leader of Mercurial government, are in the highest terrace, a single story high.

Terminator features in Blue Mars and The Memory Of Whiteness and the short story Mercurial in the short story collection Vinland the Dream.