Blek le Rat (pronounced [blɛk lə ʁa]; born Xavier Prou,[1] 1952)[2] is a French graffiti artist.

Blek's oldest preserved street art graffito, a 1991 replica of Caravaggio's Madonna di Loreta, which he dedicated to his future wife Sybille, was rediscovered behind posters on a house wall in Leipzig, Germany, in 2012.

From that point on, he has worked exclusively with pre-stenciled posters, citing the speedier application of the medium to walls, as well as lessened punishment should he be caught in the act.

[1] He has had a great influence on today's[update] graffiti-art and "guerilla-art" movements, the main motivation of his work being social consciousness and the desire to bring art to the people.

[5] In 2006 he began his series of images representing the homeless, which depict them standing, sitting, or lying on sidewalks, in attempts to bring attention to what he views as a global problem.

Blek le Rat has nonetheless expressed preference for the streets over galleries, stating the integrity of an artist is to be seen by as many people as possible, not being sold or recognized in a museum.