Stencil-assisted oxygen reactive ion etching is a low-cost and parallel process for the replication of micrometric and nanometric patterns in any organic material. This lithography process allows the patterning of organic material non sensitive to electronic or optical radiations, sensitive to solvents, or already patterned which cannot be patterned by conventional lithography methods. We demonstrate the versatility of stencil-assisted reactive ion etching though 3 examples. First to define 500 nm holes in PMMA. Secondly, the fabrication step has been integrated in a lift-off process of metal or molecular self-assembled monolayers. We finally apply stencil-assisted reactive ion etching to pattern an assembly of 100 nm latex nanoparticles.