Lasthenes () or Leosthenes (ÃÂõÃÂÃÂøÃÂý÷ÃÂ) or Leosthenion (ÃÂõÃÂÃÂøÃÂýùÿý) or Leostheneion (ÃÂõÃÂÃÂøÃÂýõùÿý) or Sosthenion (ãÃÂÃÂøÃÂýùÿý) was a town of ancient Thrace, inhabited during Roman and Byzantine times. Pliny the Elder records the name as Casthenes, which is generally taken to be a corruption of Lasthenes or Leosthenes.
Its site is located near ðstinye in European Turkey.