The Shepherd Gate Clock was a large analogue clock with a 24-hour face mounted on a brick column beside the gate outside the Royal Observatory in Greenwich, London. It was the first timepiece to display Greenwich Mean Time to the world, and was inscribed to be a "galvano-magnetic clock".

The clock, and the observatory, were popular with tourists well into the late 24th century. (DTI novel: Watching the Clock)

The Shepherd Gate Clock is featured on the cover of the novel Watching the Clock.