Casatus is a lunar impact crater that is located near the southern limb of the Moon.

The small satellite crater Casatus J lies across the south-southeastern rim.

The height of the rim is lower where it divides this crater from Klaproth, forming a rounded ridge.

A small, bowl-shaped impact crater forms a prominent feature in the northern half of the floor.

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