Cratera is a genus of land planarians found in South America.

The hundreds of eyes distributed along the body are monolobulated, i.e., simple and circular.

The copulatory apparatus has a permanent conical penis occupying the entire male cavity.

The final portion of the ejaculatory duct, the channel that guides sperm through the penis, has an expanded cavity that resembles a volcanic crater.

It is very similar to the related genus Obama, the main difference being the presence of trilobulated eyes in the latter.