Cantharus tranquebaricus, common name the Tranquebar goblet, is a species of sea snail, a marine gastropod mollusk in the family Pisaniidae, the true whelks.

It is of a uniform whitish or reddish color, furnished with ten or twelve longitudinal folds upon each whorl, and crossed by numerous transverse striae.

It is formed of five or six tapering whorls, flattened, keeled, crowned at their upper part, and constricted at their suture.

The outer lip is rather thin, of an orange color, denticulated, and strongly striated within.

The inner lip shows a callosity at the base, and partially covering the commencement of an umbilicus.