Stéphane Christophe Mony (or Stéphane Flachat, or Mony-Flachat, 14 February 1800 – 10 March 1884) was a French railway engineer, company president and politician.
He was involved in the Saint-Simonian movement when a young man.
He was trained as an engineer, and he and his half brother Eugène Flachat built the Paris-Saint Germain and Paris-Versailles railway lines between 1833 and 1840.
He was then appointed head of the Commentry mining company, later Commentry-Fourchambault, a position he held until his death.
He was elected to the legislature towards the end of the Second French Empire, from 1868 to 1870.
He did not succeed in getting reelected in the French Third Republic.