Rhamnus or Rhamnous () or Rhamnuntus or Rhamnountos (Ῥαμνοῦντος) was a deme of ancient Attica, belonging to the tribe Aeantis. It derived its name from a thick prickly shrub, which still grows upon the site. The town stood upon the eastern coast of Attica, at the distance of 60 stadia from Marathon, and upon the road leading from the latter town to Oropus. It is described in the "Periplus of Pseudo-Scylax" as a fortified place; and it appears from a decree in Demosthenes to have been regarded as one of the chief fortresses in Attica. It was still in existence in the time of Pliny the Elder.