Tyrannomolpus is a genus of leaf beetles in the subfamily Eumolpinae.

T. rex is the largest chrysomelid beetle species endemic to New Zealand, measuring between 9.7 and 11.9 mm, and may be an example of island gigantism.

Tyrannomolpus is closest to the genus Pilacolaspis from the mainland of New Zealand.

[1] The generic name is a combination of the dinosaur genus name Tyrannosaurus and the suffix "molpus", referring to the relative large size of the genus to other chrysomelids endemic to New Zealand.

[1] A single specimen of the species was collected from Meryta sinclairii (also known as the puka), a tree endemic to the Three Kings Islands.