Gassendi is a large lunar impact crater feature located at the northern edge of Mare Humorum.

The outer rim is worn and eroded, although it retains a generally circular form.

A smaller crater – Gassendi A – intrudes into the northern rim, and joins a rough uplift at the northwest part of the floor.

In the southern part of the crater floor is a semi-circular ridge-like formation that is concentric with the outer rim.

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