This list of fossil arthropods described in 2009 is a list of new taxa of trilobites, fossil insects, crustaceans, arachnids and other fossil arthropods that have been described during the year 2009, as well as other significant discoveries and events related to arthropod paleontology that occurred.

Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1915.