恐头兽亚目（学名：Dinocephalia）是个大型早期兽孔目演化支，繁盛于中二叠纪的瓜达鹿白阶，但之后灭绝而且没有留下任何后代。

除了巴莫鳄亚目与始巨鳄科以外，恐头兽类是兽孔目中最原始的物种，但仍拥有牠们的独特特征。牠们保有很多跟牠们的盘龙目祖先一样的原始特征（例如：没有次生颚，小型齿骨），但是牠们也有许多兽孔目的较高端特征，像是扩大的肠骨与更直立的四肢。牠们包括肉食性、草食性、杂食性动物，有些是半水生动物，有些是完全陆生动物。恐头兽类也是二叠纪中期的最大动物之一，只有最大的卡色龙科与锯齿龙科的体型比得上或超越她们。

Dinocephalia is a clade of large-bodied early therapsids that flourished for a brief time in the Middle Permian between 272 and 260 million years ago (Ma), but became extinct leaving no descendants. Dinocephalians included both herbivorous and carnivorous forms. Many species had thickened skulls with many knobs and bony projections. Dinocephalian fossils are known from Russia, China, Brazil, South Africa, and Zimbabwe.