Cassegrain is a lunar impact crater that is located on the far side of the Moon, beyond the southeastern limb.

It lies to the southeast of the larger crater Lebedev, and to the northeast of the comparably-sized Priestley.

The floor is level and mostly featureless, except for some deposits in the northwest corner.

The crater features prominently in the science fiction novel "The Cassandra Project," by Jack McDevitt and Mike Resnick, Ace Books, New York, 2012.

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