Mercator is a lunar impact crater that is located on the southwestern edge of Mare Nubium, in the southwest part of the Moon.

It was named after 16th-century Southern Dutch cartographer Gerardus Mercator.

[1] It is located to the southeast of the crater Campanus, and the two are separated by a narrow, winding valley.

The interior floor has been flooded by lava in the past, leaving a relatively smooth and featureless surface.

[2] By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Mercator.