"John Doe" is a way to speak about an anonymous person.  Sometimes it refers to the average guy on the street, sometimes to an unidentified body that’s been found. In French, there are different ways to say "John Doe" depending on the circumstance. Check them out below…

Monsieur/Madame Tout-le-monde (literally, Mr./Mrs. Everybody) is the equivalent of "the man/woman on the street" in English.

"Monsieur X" (Mr. X) is used to keep a person anonymous like "John Doe". It can also refer to a wanted person.

"X" refers to an unidentified body and can also refer to an unidentified criminal.

"Monsieur Untel/Madame Unetelle" (Mr./Mrs. So-and-So) is said in casual conversation about someone whose name we don’t know. "Monsieur/Mme Tartempion" is another version of "Untel/Unetelle". The name originates as a character in a play by Feydeau in the 1840’s. It’s an actual family name but the play made it famous and funny.

"Le citoyen Lambda" is used to speak about the average guy. It’s like "John Smith" or "the average Joe". 

A French word that’s a little more pejorative for the average guy is "Duchmol" or "Monsieur Duchmol". This would be similar to "Joe Schmoe" in the US.

"Trucmuche", "Truc-machin", "Machin-chose" are used when we can’t remember the name of the person.  It’s the equivalent to Mr. What’s-his-name. "Truc", "machin’, "chose" are the equivalent to thingamajig.

Feel free to share terms for "John Doe" in your language in the comments below.

Mama Lisa

Thanks to Monique Palomares for helping me with this post. Monique works with me on the French and Spanish versions of Mama Lisa’s World.