Lecanora cenisia is a species of crustose lichen in the family Lecanoraceae, first described by the Swedish lichenologist Erik Acharius in 1810 and named after Mont Cenis where it was discovered. The lichen forms a cream-white to pale grey granular thallus with distinctive red-brown to black (fruiting bodies) (apothecia) that feature persistent thalline margins containing conspicuous crystal clusters. It produces secondary metabolites including atranorin, chloroatranorin, and roccellic acid, which yield characteristic chemical reactions in spot tests. In the United Kingdom, it occurs locally on silica-rich rocks in shaded or sheltered crevices throughout Britain's upland areas and offshore islands, and serves as a host for the lichenicolous fungus Carbonea supersparsa.

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