Katyayana was a Sanskrit grammarian and mathematician. His work, Varttika is an elaboration on Panini's Astadyayi. He also composed one of the later Sulba Sutras, a series of nine texts on the geometry of altar constructions, dealing with rectangles, right-sided triangles, rhombuses, etc. His work included in the Kalpasutra of Sukla-Yajurveda. Some scholers are of openion that Katyayana is same as the vararuchi of Vikramadity period. If this is to be accepted, we should also accept that some of the work is older and there can be many vararuchi/Katyayana.

Katyayana was a deciple of Sage Shaunaka. Katyayana is the authors of the Vidhanas for the Yajur Vedas. He also worked on the Anukramanis (Anukramanis tell us about the devatas, rshis, chandas, anuvakas and sukthas) and the Pratisakhyas. His work Katyayana Smriti is a remembered text and is included in one of the 18 smriti literature.