Brachyopterus is a genus of prehistoric eurypterid of the family Rhenopteridae.

It is one of the earliest known eurypterids,[1] having been recovered from Middle Ordovician deposits in Montgomeryshire, Wales.

[2] Brachyopterus is distinguished by its small size, compound eyes with axes converging anteriorly on a subtrapezoid to subpentagonal prosoma (head).

All of its legs are walking legs; the first three pairs are short with spines, except when modified into clasping organs; the last two pairs are moderately long, keeled and tapering in width to terminal claws.

The last leg falls short of the penultimate abdominal segment.