兽头亚目（学名：Therocephalia）意为「兽的头部」，是兽孔目兽齿类的一个已灭亡演化支，存活于二叠纪中晚期到三叠纪。兽头亚目以牠们巨大的头骨与牙齿为名，牠们可能是群成功的肉食性动物。

尽管合弓纲通常被称为似哺乳爬行动物，牠们并不是爬行动物演化支的一部分。兽头亚目与犬齿兽亚目的关系亲近，而犬齿兽亚目演化出哺乳类；这层关系有者有解剖学上的证据，可能包括胡须与毛发。尽管发现化石，但兽头亚目的内部演化关系、解剖结构、生理机能上，还有许多无解的问题存在。

南非卡鲁盆地发现大量的兽头亚目化石，俄罗斯、中国、南极洲也有发现兽头类化石。在二叠纪中期，兽头类起源于盘古大陆南部，但就像犬齿兽类一样，快速散布到盘古大陆各处。许多兽头类在二叠纪-三叠纪灭绝事件中灭亡，少数真兽头类的物种存活到三叠纪早期并继续多样性发展。残活下来的兽头类在三叠纪中期灭亡，可能因为气候变迁，以及肉食性犬齿兽类、多样性的爬行动物的竞争有关。

Therocephalia is an extinct suborder of eutheriodont therapsids from the Permian and Triassic. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their teeth, suggest that they were carnivores. Like other non-mammalian synapsids, therocephalians are described as mammal-like reptiles. Therocephalia is the group most closely related to the cynodonts, which gave rise to the mammals. This relationship takes evidence in a variety of skeletal features. The phylogeny of therocephalians has been disputed, as the monophyly of the group and the relationships of its members are unclear.