A mosaic virus is any virus that causes infected plant foliage to have a mottled appearance. Such viruses come from a variety of unrelated lineages and consequently there is no taxon that unites all mosaic viruses.

Virus species that contained the word ‘mosaic’ in their English language common name are listed below, though with the nomenclature and taxonomy of the ICTV 2022 release. However, not all viruses that may cause a mottled appearance belong to species that include the word “mosaic” in the name.^{[citation needed]}