Eubranchus occidentalis is a species of sea slug or nudibranch, a marine gastropod mollusc in the family Eubranchidae.

[2] This species was described from Monterey Bay, California.

It is considered by some authors to be a synonym of Eubranchus rustyus.

[3] MacFarland reports that this nudibranch feeds on the hydroid Hydractinia, which grows on the holdfasts of Stephanocystis osmundacea.

[1]