Najaceras is a genus of straight, slender endocerid known only from the Whiterockian age Oil Creek Limestone of Oklahoma, introduced and named by Rousseau Flower in 1971 and further described by him in 1976.

Najaceras is characterized by a longitudinal mound of material that runs forward from the apical region along the inside of the top of the siphuncle known as a dorsal process.

The process is bisected in the lower port by which is known as a blade which bifurcates upwardly from about the middle.

Najaceras probably gave rise to the similar Meniscoceras which also has a dorsal process.

Najaceras comes from "naja", the word for the crescent at the bottom of the Navajo squash blossom or wedding necklace.