Polacanthinae is a subfamily of ankylosaurs, most often nodosaurids, from the Late Jurassic through Early Cretaceous of Europe and potentially North America and Asia.

If Polacanthus, and by extent Polacanthinae, falls outside either family-level clade, then the -inae suffix would be inappropriate, and the proper name for the group would be the informally defined Polacanthidae.

[3] The family Polacanthidae was named by Ernst Jaekel in 1910 to refer to a group of ankylosaurs which seemed to him intermediate between the ankylosaurids and nodosaurids.

The first comprehensive study of 'polacanthid' relationships, published in 2011, found that they are either an unnatural grouping of primitive nodosaurids, or a valid subfamily at the base of Nodosauridae.

[1][7][4][6][8][9][10] Antarctopelta Mymoorapelta Anoplosaurus Hylaeosaurus Tatankacephalus Horshamosaurus Zhejiangosaurus Struthiosaurus languedocensis Struthiosaurus austriacus Hungarosaurus Animantarx Niobrarasaurus Nodosaurus Pawpawsaurus Sauropelta Silvisaurus Stegopelta Texasetes Edmontonia Panoplosaurus Hoplitosaurus Gargoyleosaurus Gastonia Peloroplites Taohelong Polacanthus While the clade is frequently referenced in literature, a majority of taxa considered to be polacanthines have instead been found to not form any natural groups with Polacanthus, representing both primitive nodosaurids, primitive ankylosaurids, or outside the Nodosauridae-Ankylosauridae clade.