Konstantinas Sirvydas (rarely referred as Konstantinas Širvydas;[1] Latin: Constantinus Szyrwid; Polish: Konstanty Szyrwid; c. 1579 – August 23, 1631) was a Lithuanian[2] religious preacher, lexicographer, and one of the pioneers of Lithuanian literature[3] from the Grand Duchy of Lithuania, at the time a confederal part of the Polish-Lithuanian Commonwealth.

Famous for his eloquence, Sirvydas spent 10 years of his life preaching sermons at St. Johns' Church in Vilnius (twice a day – once in Lithuanian and once in Polish).

Between 1623 and 1624 he also briefly served as the deputy rector of his alma mater, after which he continued as a professor in theology, liberal arts, and philosophy.

He published his trilingual Polish-Lithuanian-Latin dictionary Dictionarium Trium Lingvarum in usum Studiosæ Iuventutis, one of the first such books in Lithuanian literary history some time before 1620.

A decade later, in 1629, he published the first volume of a collection of his sermons entitled Punktai sakymų, and later translated them into the Polish language as Punkty kazań.