Rhesus may refer to:

  • Rhesus of Thrace, a king in Greek mythology
  • S. Vivianus Rhesus, a Roman governor of Thrace
  • In Greek mythology, a river-god, son of Oceanus and Tethys
  • Rhesus (play), the Ancient Greek tragedy thought to have been written by Euripides
  • rhesus macaque, also known as the rhesus monkey
  • Rhesus factor, associated with a blood type, named for the monkey
  • Rh disease, also known as Rhesus disease
  • 9142 Rhesus, an asteroid
  • Rhesus Glacier