Marie Dompnier is a French actress, singer and director born in 1980 in Toulouse, Haute-Garonne, in France, best known both in France and internationally for her role as Lieutenant Sandra Winckler in the TV series Witnesses.

Witnesses is a French police procedural television series, created by Marc Herpoux and Hervé Hadmar, that premiered in Belgium on La Une on 22 November 2014. Set in the coastal town of Le Tréport in Normandy, France, police detectives Sandra Winckler and Justin investigate when bodies of murder victims are unearthed and left for discovery in the show homes of a housing developer. Former chief-of-police, Paul Maisonneuve, is implicated. This series was later broadcast in France on France 2 from 8 March 2015, and from 1 May 2015 Netflix began streaming a subtitled version in the United States. Channel 4 broadcast the series in the United Kingdom from 22 July 2015.