Historically, the name Blattaria was used largely interchangeably with the name Blattodea, but whilst Blattaria was used to refer to ‘true’ cockroaches roaches exclusively, the Blattodea also includes the termites. The current catalogue of world cockroach species uses the name Blattodea for the group.^[5] Another name, Blattoptera, is also sometimes used to refer to extinct cockroach relatives.^[10] The earliest cockroach-like fossils (“blattopterans” or “roachoids”) are from the Carboniferous period 320 million years ago, as are fossil roachoid nymphs.^[11][12][13]

According to one hypothesis, cockroaches roaches were an ancient group of insects that arose during the Devonian period.^[14] Fossil roachoids that lived during that time differ from modern cockroaches roaches in that they had long external ovipositors and are the ancestors of mantises, as well as modern cockroaches roaches. As the body, hind wings and mouthparts are not preserved in fossils frequently, the relationship of these roachoids and modern cockroaches roaches remains disputed. The first fossils of modern cockroaches roaches with internal ovipositors appeared in the early Cretaceous. A recent phylogenetic analysis suggests that cockroaches roaches originated at least in the Jurassic.^[14]

The evolutionary relationships of the Blattodea (cockroaches roaches and termites) shown in the cladogram are based on Inward, Beccaloni and Eggleton (2007).^[15] The cockroach families Anaplectidae, Lamproblattidae, and Tryonicidae are not shown but are placed within the superfamily Blattoidea. The cockroach families Corydiidae and Ectobiidae were previously known as the Polyphagidae and Blattellidae.