Theta chariessa is a species of sea snail, a marine gastropod mollusk in the family Raphitomidae.

The shell is faintly, shortly, and obliquely ribbed, with a high, subscalar, small-pointed spire, and a slightly tumid little-contracted base, produced into a long narrow siphonal canal.

There are further obsolete lines of growth, which in the sinus area are strong, and at the suture form sharp little folds parted by wide unequal intervals.

It is bordered by the blunt angulation forming the keel, which is greatly strengthened by the prominence of the origin of the longitudinal ribs.

From the keel downwards the shell is covered by superficial, flattened, irregular, and unequal threads parted by narrower shallow furrows.

The spire is conical, high, rather narrow, subscalar, sometimes scalar from the squareness with which the sinus area stands out in the upper whorls.

The outer lip is pretty regularly arched from the body to the siphonal canal, from which point it is drawn out rather straight.