The first one I'd put on my list would be:

Gestes et Opinions du Docteur Faustroll, 'pataphysicien. Roman néo-scientifique suivi de spéculations.

by Alfred Jarry, written in the late 19th century, published in 1911. It's the founding text of 'Pataphysics, and as influential on later currents like dadaism, absurdism, surrealism, Ouxpo (and eventually even pop music - eg: the Beatles, and in arts people like Duchamp, Dali, Ernst, Man Ray, Miro, Escher, or Borgès, Ionesco, Queneau, Vian, Beckett, Arabal, Calvino in drama/literature) as the novel itself is little known outside literary circles.

'Pataphysics was defined by Jarry as "the science of imaginary solutions, which symbolically attributes the properties of objects, described by their virtuality, to their lineaments."