Smilax glauca, the cat greenbriar or catbriar, is a woody vine in the family Smilacaceae. It is native to central and eastern portions of the United States as well as Mexico, where it is a common and conspicuous part of the forest vegetation.

Smilax glauca has prickly stems and climbs by means of tendrils. Leaves are notably gray-glaucous to whitish beneath. It commonly inhabits wooded areas and fences and is often found growing with other species of Smilax. The plants tend to be evergreen in the more southern United States.