Rhenopterus is an extinct prehistoric eurypterid.

Fossils of Rhenopterus have been recovered from deposits of Lower Devonian age in Germany.

[1] Rhenopterids were small, characterized by scattered tubercules and knobs on the outer surface of the exoskeleton.

The prosoma (head) was subtrapezoidal, with arcuate compound eyes on parallel axes.

The male genital appendages were short with two distal spines.