Eotyrannus (meaning "dawn tyrant") is a genus of tyrannosauroid theropod dinosaur hailing from the Early Cretaceous Wessex Formation beds, included in Wealden Group, located in the southwest coast of the Isle of Wight, United Kingdom.

In July 2018 Darren Naish, a colleague of Hutt who helped produce the preliminary description, created a GoFundMe fundraiser in order to release a monograph of the specimen, which received well over its goal.

[6] Proceratosaurus bradleyi Kileskus aristotocus Guanlong wucaii Sinotyrannus kazuoensis Juratyrant langhami Stokesosaurus clevelandi Dilong paradoxus Eotyrannus lengi Bagaraatan ostromi Raptorex kriegsteini Dryptosaurus aquilunguis Alectrosaurus olseni Xiongguanlong baimoensis Appalachiosaurus montgomeriensis Alioramus altai Alioramus remotus Tyrannosauridae A 2014 analysis found Eotyrannus to be a megaraptoran closely related to taxa like Megaraptor.

[3] Juratyrant Stokesosaurus Yutyrannus Xiongguanlong Aniksosaurus Fukuiraptor Australovenator Orkoraptor Dryptosaurus Bistahieversor Tyrannosauridae In 2024, Andrea Cau recovered Eotyrannus as a sister taxon of Proceratosauridae, distant in relation from Megaraptora.

In the Wessex Basin, sedimentological evidence, as well as fossils such as mud-cracks, suggests that the area experienced a warm, equable paleoclimate with a mean annual temperature of 20–25 °C with low seasonal rainfall.

Watson and Alvin (1996) and Allen (1998) showed that the Wessex Formation flora was both fire and drought resistant and suggested that it was adapted to a seasonal climate with periods of marked aridity.

[9] The Wessex Formation possessed a wide array of fauna, including many other dinosaurs such as the carcharodontosaurian Neovenator, the compsognathid Aristosuchus; the medium size spinosaurids Riparovenator and Ceratosuchops; the basal neornithischian Hypsilophodon; the ornithopods Iguanodon, Mantellisaurus, Brighstoneus, and Valdosaurus; the sauropods Ornithopsis, Eucamerotus, and Iuticosaurus; and the ankylosaur Polacanthus.