Tetraceratops insignis ("four-horned face emblem") is an extinct synapsid from the Early Permian that was formerly considered the earliest known representative of Therapsida, a group that includes mammals and their close extinct relatives.

According to a 2020 study, it should be classified as a primitive non-therapsid sphenacodont rather than a genuine basal therapsid.

When it was discovered and described in 1908, the skull was still embedded in a matrix, and only the premaxilla and prefrontal pairs were visible.

Tetraceratops was originally identified as a member of a group called Pelycosauria, an evolutionary grade of synapsids more basal than therapsids.

[3][5][6][7] However, a recent study by Spindler concluded that no convincing morphological evidence could be made for a therapsid placement of Tetraceratops and that this genus was better placed as a basal sphenacodontian.